Bought a 85 GMC 4x4 6" lift ...it has a modified 700r4(Automatic) using a B&M trans kit..TCI .500 boost valve..1-2 servo..So heres my problem ..when I drive the truck the tranny shifts hard into 2nd.. If dont let off the gas it will cherp the tires going into 2nd ..If I let off the gas at about 2500rpm it Sh!tfs fine into 2nd or if I stay on the gas hard it will shift ok at around 4000rmp..same goes for 2nd to 3rd if you dont feath the gas just right or get the rpms up to 4000 it will bang into gear..It has a GM 14 bolt 10.5 rear axle w/ 4.56 gears and detroit locker..The guy I got the truck from said it shifts like that cus of the 4.56 gears?..but I was thinking that the 10.5 w/4.56 gears was a command chevy rear end not modified???...but I've been told diffrent stories...I was told its because of the shift kit..Its the 4.56 gears..Its the tranny..All I know is its not good on the rear end, drive shaft or tranny..Befor I get into this Im hoping for some feed back...thanks

Have you ever heard of Lucas Transmisson repair? It is some good stuff you can get it at most part stores i just get it at autozone. But it is some real thick stuff and it does a great job for hard shifts.

Jordan B.