Picked up a 4R75 from an 04 Mustang today.
Going to have a professional rebuild done with some upgraded components. Apparently these transmissions are pretty stout from the factory so a refresh with some higher end parts should suffice for the first power level of this build.
Future upgrades will include a stall, rpm to be decided once we shakedown the motor a little. If need a transbrake may find its way in as well.
I think initially I will run a Transgo manual valve body. I know a few guys personally that are having good luck with the Baumann controller and I may end doing that before too long.
I'll need a crossmember from a 05-09 GT, and I still have to source a driveshaft. For now the rest of the driveline will stay as is, but a Locker is in the mid term plans since the Tlok is starting to fail.