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Author
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Topic: how much power can an 8 inch rear handle!!
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64coupe
Journeyman Posts: 76
From: Langhorne, Pennsylvania, United States of America
Registered: Sep 2002
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posted 03-08-2005 06:04 PM
   
how much power can an 8 inch rear handle if built right? I have a 306 with a wide ratio toploader and 3.55:1 gears in my 8 inch rear. i an thinking of getting an auburn posi unit for the rear. i have 26 inch tall drag radials...no slicks. if any one can hel me it would be greatly appreciated. thanks
-Steve
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johnmustang
Gearhead Posts: 5804
From: British Columbia , Canada
Registered: Nov 2001
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posted 03-08-2005 06:34 PM
It will handle a heck of alot more then you will be throwing at it. You asked how much it could handle if "Built Right", it will handle between 500 - 700 HP. If I remember properly Alex`s 65 (MoneyMaker) has an 8 inch that is "Built Right" and he has had no problems that I can remember reading about. Go with the 8 inch and enjoy it.------------------
JOHN
65 FASTBACK 2+2.....14.44 @ 107mph 1/4
87 TAURUS WAGON
03 F150 XLT SUPER CREW 4X4 SHORT BOX
Member:Vancouver Island Mustang Association
M&M #1710
65 FASTBACK
2003 F150 XLT SUPER CREW 4X4
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64coupe
Journeyman Posts: 76
From: Langhorne, Pennsylvania, United States of America
Registered: Sep 2002
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posted 03-08-2005 06:46 PM
i have been told by alex to use studs for the bearing caps which is a wise idea to get a better torque setting. i plan on using the auburn pro series posi unit. anything else to take into consideration?
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Steve-UK
Gearhead Posts: 197
From: Wickford, Essex, England
Registered: Jan 2003
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posted 03-08-2005 07:04 PM
I have just built an eight inch, Currie's do a pinion support that allows a larger inner bearing to be fitted, and better oiling.Billet Pinion Support
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Moneymaker
Administrator Posts: 25432
From: Lyons, IL, USA
Registered: May 99
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posted 03-08-2005 09:43 PM
About 450 HP with slicks is what the best one can stand.
With street tires, a well prepped 8 inch can hold up to almost infinate HP.------------------
Alex Denysenko
Co-Administrator and Moderator NHRA/IHRA/SRA member and licensed Superstock driver
NHRA and IHRA SS/LA & SS/MA National Record Holder '00,'01,'02,'03,'04 &'05
First SS/MA in the TENS!
IHRA division 5 Superstock Champion
Fleet of FoMoCo products including 88 ASC McLaren Mustang #28 The Barry of BarrysGrrl Quote #1: "I never met a magazine mechanic I liked."
Quote #2: "Make sure brain is in gear before engaging mouth!"
Quote #3: "If you can't run with the big dogs, stay on the porch!"
www.moneymakerracing.com
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64coupe
Journeyman Posts: 76
From: Langhorne, Pennsylvania, United States of America
Registered: Sep 2002
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posted 03-08-2005 10:10 PM
has anyone used an auburn pro series differential. just curious how long they last and it anyone has had any problems with them. thanks
-Steve
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Fastymz
Moderator Posts: 18491
From: Reno Nv USA MEM#1240
Registered: Apr 2001
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posted 03-08-2005 10:24 PM
quote:
Originally posted by Moneymaker:
About 450 HP with slicks is what the best one can stand.
With street tires, a well prepped 8 inch can hold up to almost infinate HP.
Alex is that RWHP ? also that would be after all the trick parts have been added. How about stock ? ------------------
oddly obsessed with big scoops on little Mustangs 65 coupe 351w C4 Big Boss 429 hood scoop,8" 3.40 TracLoc. My Pics
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steve'66
Gearhead Posts: 8784
From: Sonoma,CA,USA
Registered: Mar 2000
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posted 03-08-2005 11:16 PM
quote:
Originally posted by johnmustang:
If I remember properly Alex`s 65 (MoneyMaker) has an 8 inch that is "Built Right" and he has had no problems that I can remember reading about.
I don't think Alex is running a 8" in MoneyMaker.... 
SteveW
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johnmustang
Gearhead Posts: 5804
From: British Columbia , Canada
Registered: Nov 2001
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posted 03-09-2005 12:33 AM
quote:
Originally posted by steve'66:
I don't think Alex is running a 8" in MoneyMaker.... SteveW
My mistake, I thought I saw a post a little while back saying that Alex was running an 8", maybe it was that he was running a C4. Now I just don`t remember  , it really sucks getting old . Can somebody get me my geritol and a mug of warm milk, I am going to bed ------------------
JOHN
65 FASTBACK 2+2.....14.44 @ 107mph 1/4
87 TAURUS WAGON
03 F150 XLT SUPER CREW 4X4 SHORT BOX
Member:Vancouver Island Mustang Association
M&M #1710
65 FASTBACK
2003 F150 XLT SUPER CREW 4X4
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Moneymaker
Administrator Posts: 25432
From: Lyons, IL, USA
Registered: May 99
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posted 03-09-2005 01:45 AM
I always speak in real horse power figures produced by the engine.
At the flywheel or BHP.
Not bogus or bullsh*t numbers spwewd from a chassis dyno.
Too many variables. ------------------
Alex Denysenko
Co-Administrator and Moderator NHRA/IHRA/SRA member and licensed Superstock driver
NHRA and IHRA SS/LA & SS/MA National Record Holder '00,'01,'02,'03,'04 &'05
First SS/MA in the TENS!
IHRA division 5 Superstock Champion
Fleet of FoMoCo products including 88 ASC McLaren Mustang #28 The Barry of BarrysGrrl Quote #1: "I never met a magazine mechanic I liked."
Quote #2: "Make sure brain is in gear before engaging mouth!"
Quote #3: "If you can't run with the big dogs, stay on the porch!"
www.moneymakerracing.com
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Rory McNeil
Gearhead Posts: 1534
From: Surrey, B.C. Canada
Registered: Nov 2000
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posted 03-09-2005 02:34 AM
Personally, I don`t much care for the Auburns. First off, they are a cone style posi, which means that they basically eat themselves up as they wear, filling the gear oil with metal particles. They are also not rebuildable, so when it starts slipping, you need another unit. They also don`t seem to hold up very well, at least with a stickshift & slicks. My buddy has a mid 12 second 79 Mustang, with a 302 & at the time, a T5. When his OE 8.8 traction lok started slipping, he "upgraded" to a new Aburn "Pro Series" posi. In 2 weeks, it was a broken piece of scrap metal. No warrenty, & he could not purchase the parts to repair it. (He works in a diff. shop that sells Auburns). He then built a 31 spline truck 8.8 trac. lok, & other than replacing the clutches once since, it has been fine for 5 or 6 seasons now. ------------------
78 Fairmont 428 4 speed 10.20@130mph
80 Fairmont 302 5 speed 12.8@105mph
85 Mustang NHRA M/Stock 302 5speed. [email protected]
59 Meteor (Canadian Ford) 2 dr sedan 332, auto
74 F350 ramp truck 390 4spd
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Fastymz
Moderator Posts: 18491
From: Reno Nv USA MEM#1240
Registered: Apr 2001
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posted 03-09-2005 09:06 PM
How well will a stock 8" hold up behind my motor and C-4 trans 2200 stall with slicks?
Or Dot street/strip tires?Or should I just stick to street tires. Until I change out the rear end? ------------------
oddly obsessed with big scoops on little Mustangs 65 coupe 351w C4 Big Boss 429 hood scoop,8" 3.40 TracLoc. My Pics
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Bloose
Gearhead Posts: 604
From: Milwaukee, WI
Registered: Dec 2001
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posted 03-09-2005 09:44 PM
I have an Auburn Pro Posi in my '68 W/8". It does the one wheel peel a lot at this point. It's about 2 season old. I guess they have a REX program where they'll replace them for less than a rebuild. I think there OK for a street car but mine did not hold up to my drag radials. I'm going to a 9" and Detroit.B-loose
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Moneymaker
Administrator Posts: 25432
From: Lyons, IL, USA
Registered: May 99
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posted 03-09-2005 11:29 PM
Best carrier for a 8 inch is a Detroit Locker.
FYI, MM has a nine inch.
It came with one from the factory and it's still there. ------------------
Alex Denysenko
Co-Administrator and Moderator NHRA/IHRA/SRA member and licensed Superstock driver
NHRA and IHRA SS/LA & SS/MA National Record Holder '00,'01,'02,'03,'04 &'05
First SS/MA in the TENS!
IHRA division 5 Superstock Champion
Fleet of FoMoCo products including 88 ASC McLaren Mustang #28 The Barry of BarrysGrrl Quote #1: "I never met a magazine mechanic I liked."
Quote #2: "Make sure brain is in gear before engaging mouth!"
Quote #3: "If you can't run with the big dogs, stay on the porch!"
www.moneymakerracing.com
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64coupe
Journeyman Posts: 76
From: Langhorne, Pennsylvania, United States of America
Registered: Sep 2002
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posted 03-09-2005 11:52 PM
quote:
Originally posted by Bloose:
I have an Auburn Pro Posi in my '68 W/8". It does the one wheel peel a lot at this point. It's about 2 season old. I guess they have a REX program where they'll replace them for less than a rebuild. I think there OK for a street car but mine did not hold up to my drag radials. I'm going to a 9" and Detroit.
B-loose
roughly how mnay passes did you have on it? thanks
-Steve
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johnmustang
Gearhead Posts: 5804
From: British Columbia , Canada
Registered: Nov 2001
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posted 03-10-2005 12:05 AM
quote:
Originally posted by Moneymaker:
FYI, MM has a nine inch.
It came with one from the factory and it's still there.
I remember that now Alex, I keep forgetting that M&M came with the 289 Hipo, which comes with the 9 inch. This is correct is it not or am I way off base again? ------------------
JOHN
65 FASTBACK 2+2.....14.44 @ 107mph 1/4
87 TAURUS WAGON
03 F150 XLT SUPER CREW 4X4 SHORT BOX
Member:Vancouver Island Mustang Association
M&M #1710
65 FASTBACK
2003 F150 XLT SUPER CREW 4X4
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Moneymaker
Administrator Posts: 25432
From: Lyons, IL, USA
Registered: May 99
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posted 03-10-2005 12:33 AM
Correct John.  ------------------
Alex Denysenko
Co-Administrator and Moderator NHRA/IHRA/SRA member and licensed Superstock driver
NHRA and IHRA SS/LA & SS/MA National Record Holder '00,'01,'02,'03,'04 &'05
First SS/MA in the TENS!
IHRA division 5 Superstock Champion
Fleet of FoMoCo products including 88 ASC McLaren Mustang #28 The Barry of BarrysGrrl Quote #1: "I never met a magazine mechanic I liked."
Quote #2: "Make sure brain is in gear before engaging mouth!"
Quote #3: "If you can't run with the big dogs, stay on the porch!"
www.moneymakerracing.com
IP: Logged |
johnmustang
Gearhead Posts: 5804
From: British Columbia , Canada
Registered: Nov 2001
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posted 03-10-2005 01:09 AM
quote:
Originally posted by Moneymaker:
Correct John.
Yaaahoooo, can I take a dollar out of petty cash ------------------
JOHN
65 FASTBACK 2+2.....14.44 @ 107mph 1/4
87 TAURUS WAGON
03 F150 XLT SUPER CREW 4X4 SHORT BOX
Member:Vancouver Island Mustang Association
M&M #1710
65 FASTBACK
2003 F150 XLT SUPER CREW 4X4
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64coupe
Journeyman Posts: 76
From: Langhorne, Pennsylvania, United States of America
Registered: Sep 2002
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posted 03-10-2005 11:25 AM
quote:
Originally posted by 64coupe:
roughly how many passes did you have on it? thanks
-Steve
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64coupe
Journeyman Posts: 76
From: Langhorne, Pennsylvania, United States of America
Registered: Sep 2002
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posted 03-10-2005 11:26 AM
that last post was to Bloose
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TomP
Gearhead Posts: 5710
From: Delta BC Canada
Registered: Dec 99
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posted 03-10-2005 12:21 PM
I know a guy that ran 11's with an 8" in his Mustang with nitrous on a 331" smallblock. I wouldn't trust one for that, i broke an 8" in my 65 Falcon with a 200 six and automatic on skinny 14" radial tires.... on the street. It busted the caps off the back. Also on the posi subject, the Auburns are poo but no Ford posi is bulletproof, if your tractionlok starts doing the one wheel peel, STOP. Rebuild it. I spent all day yesterday trying to take apart three broken 9" burnout contest special posis. The spider gears starve for oil and weld themselves to the shafts which spin in the case and ruin it, clutches are worn right through the steel plates then the metal shrapnel takes out the gears and bearings.
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89_coupe
Gearhead Posts: 215
From: Ontario (Upstate), NY
Registered: Mar 2001
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posted 03-11-2005 11:12 AM
I feel I pretty much have the most experience in this area. I used an 8" rear as long as I could and as long as I could afford to break until I finally went to a 9". There are two 8" pumpkins and don't even consider the early one with anly a couple ribs. The pinion will get yanked out through the front an any hard launch. I did 2 of them (one on a Sat and the other the next Sat) while only maybe in the high 1.5 60ft at 300#s w/driver and C4 footbraking. This was after I broke my first pumpkin which was a late model heavy ribbed and it pushed the carrier through the caps on a high 1.40 60ft launching on nitrous (hitting the button maybe .5-.75 second after actual launch) still on a footbrake launch. That made a mess of my carrier but the mess was contained since the housing kept the carrier inside. After blowing the carrier through the caps on the 2 weaker earlier center sections. I then went to the junk yard and got 2 more late heavy ribbed casting pigs and bought yet 2 more sets of 4.10 gears and built both of them still using cheap $12 mini spools and I could run low 11s with high 1.50 60ft times without any problems but the moment I tried nitrous before the 60ft was over the carrier would get pushed through the caps again. 5 8" pumpkins in 2 months was my limit and the 2 driveshafts from the 2 early pigs that had the pinions pulled out through the front on launch hurt my wallet and I then saved up for a 9". It cost me exactly $100 to have my 8" ends and spring perches cut off and have my 9" narrowed to the exact width of the 8" that came off using my 8" bearing ends so the 8" axles could be used until I could afford the 31 spline race axles. The spring perches off the 8" were welded on at the same place and at the same angle as they were on the 8". I got a 4.11 9" pumpkin out of a truck in the junk yard for $75 and I put my mini spool in it. That 3rd member held up to mid 1.40 60ft times at which time my axles were tweaking the splines and I went through 4 pairs during that time (I still have them ). I replaced them after they would twist one full spline. So the limit for reliability for me with an 8" rear was mid 1.50 60ft times in a fairly light 3000# race weight using an automatic not using nitrous (low 11s at 118mph). The moment I tried to launch harder the 3rd member would break instantly usually not even getting any foreward movement out of it from it breaking if I hit the button too soon. The stock 9" with stock worn out Ford 4.11 gears was trouble free through the 10.30s I was running at that time on the bottle. The quickest with the 8" was 10.50s because of not being able to launch on the bottle. This was back in the early '90 when this all happened. In the mid '90 I got the $1500 totally aftermarket Strange center section and the race axles and that has seen 1.32 60ft times and can handle much more. Early on when just in the 1.60 60ft times I learned you should gusset the rear of the spring perches on the housing or they will curl up and allow the housing to roll under pewer Back then, I was running 10.30s with no roll bar but I was told soon after to get one or at least exhaust tubing because the track was recieving complaints about my car not being safe. At that time we had what was called "Midnight Drags" in Tulsa and it was run what you brung race who you want no tech and no safety requirement AND I was taking passengers down the track too. $5 per peson to get in and anyone could race once in. 11PM-whenever in true street racing style the boards were turned off and no ET was shown. The midnight tree was a single yellow stage and a 4 tenth single yellow and a red/green bulb. True street racing and lots of money being bet. Many people racing totally drunk and a lot of fights in the pits. It was the best times I ever had (I never got into fights or raced drunk) ------------------
Kent '68 Falcon wagon stock 289
'65 Fairlane 500 wagon 10.5:1 351W
'78 Fairmont wagon 10.5:1 302
'76 Pinto wagon 392 stroke
'01 Focus SE DOHC 2.0L
'04 Explorer XLT 4.6 3.73 trac lock What is this FE fixation for which there seems to be no real cure? Something about wanting to spend twice as much money to go half as fast for one third the number of passes between explosions and not being able to find parts to fix it when it does explode. Pinto 392W 15:1, Iron Pro Topline 64/215s ported to 237cc, angle milled .115" to 52.5cc chambers with 2.08/1.6 valves, ported Super Victor, 1.72 rockers, Isky solid roller (290/300 adv, 256/266 at .050", .650" net lift, 108LSA/108 ICL), Crane Pro Series solid roller lifters, 9375 1050 Dominator, Victor water pump, billet 9 key timing set, custom 1 7/8"-2" step headers, 3.5" H-pipe and Hooker Aero Chamber mufflers, C4 w/9" 5000 stall, 4.30 gears, 28/10.5/15 MT ET Drags, 3200#s w/o driver.
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Rustang
Gearhead Posts: 726
From: Clarion PA
Registered: Nov 2000
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posted 03-11-2005 11:20 AM
Kent,
Good stuff 
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64coupe
Journeyman Posts: 76
From: Langhorne, Pennsylvania, United States of America
Registered: Sep 2002
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posted 03-11-2005 02:19 PM
89_coupe were you on full slicks? and did it usually break when you hit the juice or second gear.
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Fastymz
Moderator Posts: 18491
From: Reno Nv USA MEM#1240
Registered: Apr 2001
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posted 03-11-2005 07:15 PM
Kent, did you ever do anything to the 8" or were they all stock. If my stock later 3rd memver 8" will hold to 1.60 60's I'd be real happy. Of couse now I need to get the car to do 1.6 60's. ------------------
oddly obsessed with big scoops on little Mustangs 65 coupe 351w C4 Big Boss 429 hood scoop,8" 3.40 TracLoc. My Pics
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steve'66
Gearhead Posts: 8784
From: Sonoma,CA,USA
Registered: Mar 2000
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posted 03-12-2005 12:32 AM
Ron,Put the slicks on and you'll be at least in the 1.70s. SteveW
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Fastymz
Moderator Posts: 18491
From: Reno Nv USA MEM#1240
Registered: Apr 2001
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posted 03-12-2005 02:35 AM
quote:
Originally posted by steve'66:
Ron,Put the slicks on and you'll be at least in the 1.70s. SteveW
The slicks will be on the next time the car gets to the track.
------------------
oddly obsessed with big scoops on little Mustangs 65 coupe 351w C4 Big Boss 429 hood scoop,8" 3.40 TracLoc. My Pics
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TomP
Gearhead Posts: 5710
From: Delta BC Canada
Registered: Dec 99
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posted 03-12-2005 12:59 PM
Kent, that isn't the best way to try out parts, a damn good test though. You wreck a bunch of other stuff when the caps break. Sort of like saying "I'm not worried about these rod bolts, they are $9 a set". You would have been money ahead to have bought the 9" in the first place. Even running mid 10's on a stock 9" case is considered good!
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steve'66
Gearhead Posts: 8784
From: Sonoma,CA,USA
Registered: Mar 2000
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posted 03-12-2005 01:14 PM
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