Quite often if you clean the speed sensors they will start working again.convertiyota said:The auto should be the 4L80e. Had it in my 94 behind a 454. I bought it with about 75k on it and put about 30k on it, stock tranny as far as I know. It started sticking in 2nd gear on me once, but luckily it turned out to only be the transmission speed output sensor, $20 super easy fix. Never had any other problems with it after that.
I have +183K miles on my 97 GMC with a 4L80E with just regular fluid/filter changes, and a couple cleaning of my speed sensors.