I am having problems with a c6 transmission. I put the truck on blocks, started the engine and crawled under the truck so I could shift the transmission by hand.
1 with the transmission in park it loads the engine and makes a strange noise when you rev the engine.
2 when you shift out of park and into neutral or reverse it drives the wheels forward and if you try to go back to park it grinds and wont go.
3 if you shift from there into drive second or first the drive shaft stops spinning.
4 it will go back into park if you shift it quickly but if you stop in drive and bump it easy it starts driving the wheels again and wont go into park.
5 the down shift is not working.
The truck has been sitting for along time ( not sure how long ) and when I drove it home the transmission didn't go into third. I changed the vacuum module and the transmission was shifting quick from first to second and then into third.
Any help would be appreciated.

Thanks Jim