Quote Originally Posted by fastacton View Post
I'm not an expert on it, but I believe that the force motor operates at a different frequency and has a cleaning cycle that the '7427 doesn't support. I've heard of people using the early trans with the '7427, but not sure how long they'll last like that.
I talked with a friend of mine who is a 4L80E nut, I mean a real 4L80E nut, not just someone who likes them. So far his car (1971 Cutlass), his girlfriend's car (1988 Chevy Caprice) have 4L80Es installed, and his 1992 (I think) Old Custom Cruiser is getting a 4L80E as well, all behind Olds engines. lol

Anyway, after looking up some reference material he has it indicated that some cars had the force motor valve algorithm to keep the valve from getting stuck, however it only does this in park and it sounds like many domestically sold vehicles didn't have this enabled. Later PCMs don't seem to have this and those transmissions seem to be fine. The change in frequency also doesn't seem to be a problem from his experience.