Would you trust a company like 4 wheel parts to change your rearend gears from a 3.21 to a 3.92? I have been told nothing else need to be changed but I have to think the CPU needs to be told what gear is in the rearend to adjust part throttle shifts. What do you think?

 

I think we already told you the computer, which is actually a PCM (powertrain control module), not CPU, does not need to be reprogrammed. PM Bountyhunter for more info, he went with 4.10's.

4WheelParts is a good place to go.