Trans swap Need Help No 3rd or OD OD off light always on
I have a 1996 2500 w/5.9, 2WD auto, Trans went out, replaced with a 2001 model, changed tail section to accommodate speed sensor and such. wiring harness installed fine, 1st and 2nd feel like they work, reverse works, does not go into 3rd or OD, also OD off light on dash stays on constantly and has no affect when pushed. Was there any internal changes that needed to be made? There is no slipping or shaking, possible electrical problem or some thing not matching?