I have a 95 Z28 and the car has sat for 4 yrs. My problem is when I manually downshift to low the trans slips or feels like it goes into neutral. other than this problem the trans shifts fine. Any help will be appreciated.

 

When you start losing engine braking function, a rebuild is generally in the near future.

 

We have separate forums for various topics. This is the LT1 Based Engine Tech forum. I'll move your post to the "Drivetrain" forum.....

 

Thanks I was thinking that is what I would have to do.

 

The overun clutch alum. piston is likely cracked. You'll likely lose forward gears all together when it cracks enough. When you get it rebuilt, use the bonded pistons, not the alum. pieces.