As I recall, mind you it's been many years, on my '67 there was a harness with three wires (but only two holes in the plug) that the am radio pluged into, two wires were yellow w/ black stripe the other was light blue with a red stripe. The yellow/black was switched power and the light blue/red had power when the lights are turned on. Grounding was done independent of the underdash harness. I tapped into the lighter wire for constant power to the memory circut.If your going to use aftermarket speakers you'll have to wire them from scratch. The antenna plug should fit just fine.
If your Pioneer receiver has a separate circut for lighting, you may need to put a noise filter on it. Took me awhile to figure this out.
Make sure you double check this info. Like I said it's been MANY years since I hooked my deck up.
[This message has been edited by Moneypit (edited 12-18-2002).]
[This message has been edited by Moneypit (edited 12-18-2002).]