I have a 2002 Monte Carlo SS 3.8. I just recently replaced my transmission in my vehicle with one that I thought was from a 2003 Impala 3.8, but there was no tag on the transmission to confirm. There was faint lettering that started with 05, making me question if this transmission was actually from an 03. Upon the first test drive, the car seemed to shift fine when accelerating slowly and letting the speed build into the shift. When accelerating hard from a stop, however, there was a extremely violent shift and it felt like it slammed into gear. There were no CEL's that popped onto the dash, but there was a pending P1810, which with some research is in relation to the TFP sensor/solenoid. Too much or too little pressure within the shift. What is my best course of action? Do I need the PCM from the 05 Impala so the car can know the correct shifting points? What is that process like? Any help would be great.

 

Did you figure anything out im coming back to my project from the same time of this post, i dropped a 03 4t65e in a 01 monte that i supercharged. Im figuring out now that the valve body and sensors were changed.