Well, they SHOULD be the same. But after all this time, if anyone else owned it, or worked on it, you never know what someone might have done.
I did some up against this one time, where a 390 flywheel I got from somewhere had a bigger bolt pattern than the 360 I had, and no, it wasn't an FT flywheel, or a 428/410 flywheel that had been neutral-balanced.
I don't know for sure, but at the time, I just figured it was a year-related thing, and at some point, either with the 352, or some other reason, they went to a larger clutch.
I would get a "heavy-duty" pressure plate, NOT REBUILT, if indeed the clutch is actually slipping with the 390.
Does the flywheel have a step cut into it where the clutch plate contacts it?
I have seen different size clutchs depending upon year and parts store. But from what I have come across is the 360 came with a 10.5 inch clutch replaced with 11 at most stores. 390 had 11.5 inch clutch disc now replaced by 12. Autozone and Advance auto list 11 for 360 and 12 for 390. In either long style pressure plate or diaphram.
I have put a 12 inch 390 flywheel and clutch kit on my 360.
Forgot to add that a lot of places list the 360 parts for both. I guess the 10.5 inch clutch and their 11 inch replacements are more common.
This is what I have seen.
Last edited by fordman400; 03-25-2011 at 10:36 AM.
Reason: added statements