OK, I went to PCM4LESS website and they talked about a CASE (Crankshaft Angle Sensor Relearn) being necessary if the computer is completely rewritten with the latest GM calibration. But they also said they had loaners that have the CASE relearn disabled and it does not hurt performance. So it must not be too important?
What do you know about CASE?
Who would you get an ECM from? AutoZone? PCM4LESS?
I, personally, think AutoZone is good for car wash soap, car seat covers, etc. I wouldn't buy an electrical item from them if they were the last store on earth. I would suggest NAPA for an ECM. I'm also not a big fan of buying car parts off the internet. As for the crank re-learn, GM recommends that the following be done when installing a new PCM:
However, like i say- this is for a blank PCM. When you buy an aftermarket one, it should have all this pre-programmed.