I've got the 4L60E in my 95 Z28. The 3-4 clutch pack fried at 65k miles. I had a guy rebuild it with some good parts. (Zpack 3-4 clutch pack, heavy duty band, etc...) I also put in a 2800 stall converter because my cam. The guy also said he turned the internal line pressure up a bit for firmer shifts. I also previously had the computer custom programmed by Ed Wright. He also played with the transmission stuff in the computer. My problem since the rebuild is it won't hold 4th gear on the highway until you drive 7 or 8 miles. It will go in to 4th, but as soon as you touch the gas, the tranny goes back to 3rd. This is a huge problem for me. I am running 4:11 gears. So I have to run 4000 rpm to get 65 mph.

The guy has screwed me around repeatedly in the past 6 months about the issue. 1st he tried to tell me it was the converter locking and unlocking because of the stall speed. I know the difference between a converter locking up and a 4th to 3rd shift. He did come over and adjust something in the pan 1 night and the prob got a little better. But now he won't return my phone calls.

If anybody has any helpful info on this, it would be greatfully appreciated.