O.k so i have a 1998 GP GTP with 4T65E-HD trans but is has problems so i went and bought a transmission off a 1999 GP GT wich i beliebe is a 4T65E (Non HD)
Now both transmissions look alike but the HD has 905 S written on it and the other one has 917, Any idea what the difference is?
And i'm going to switch the differentials on both transmission to make the NON-HD an HD does anybody here done this and any luck?