I have a 2002 avalanche i replaced the trans from one from juckyard but it had a 2017 mark on in side, it is a 2002 trans. of the bell housing. any way been running and shifting . i put a 6.0 in the avalanche had the pcm adjust for the cam but now the problem. if im going up a hill or towing something. the trans winds out to 3200 rpm before shifting iinto 4th gear all other gears shift normaly going down the hill all gears shift normally so my question should the trany be rebuilt or is this the pcm programing causing this and im not hot roding it at all the cam was for towing low end power

 

Need a little more info about your combo of parts to help you out

For example, I have an '04 suburban with a 5.3 with 4.8 flat tops and a small cam 204/222 112 Stock converter Stock diameter tires are about 31" and 4.10 gears. I can lug the truck on hills at the same rpm or even lower then stock if I want to with this setup

The tune on the PCM and the combo of Parts have everything to do with how it behaves

 

It would seem that the engine doesn't have the power to pull 4th gear under that load, or the PCM needs tuning.