I'm currently running a 10L80 transmission in my swap, but I have had two separate transmissions each having pump issues. The first one had the idler gear come off the bearing in the front stator support. I ordered a reman transmission directly from GM, and now this one is having pump whining issues after only 5k miles.

So, I'm looking to swap in an 8L90 transmission instead. If I have a E92A ECM and a T87A TCM, what would I need to do to swap in an 8L90? Do I need to rework the harness? Am I able to reprogram the T87A to an 8 speed from the 10 speed, or would I need a new TCM specifically for the 8 speed?