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?

 

Rumor has it that there were indeed some electrical changes in 2000. However, when I compared the pinouts on the connectors, they were the same....... So, changing electronics in the trans may, or may not... make any difference. Be aware, that the mountings changed for the governor pressure solenoid as well... so, in order to change to the older version electronics, need some parts off the old valve body as well.