sail said:
What can I mess up that I have not already?
Never, never, never ask that...
Do you have a 1/2" chuck drill? The pilot end of the input shaft is 1/2". You can chuck your drill motor onto that, spin-up your tranny (CLOCKWISE, the same direction your engine turns -- THIS IS IMPORTANT) on the bench, and check everything, including OD function.
It would be nice to have one of those OD pressure test gauges, but it can be done without.
If it all looks (sounds) good, then mate it to the motor and take your test drive.