[WorkinLonghorn]

When I used to work in transmission shops we would first make sure it was the pan leaking and not something above by cleaning and drying the trans and letting it run (in gear) on the hoist for awhile. If the pan was leaking and any time we had a pan off for any reason we would put a straight edge across the pan mating surfaces and pay close attention to any gaps caused by distortion usually at the bolt holes. We would gently hammer the pans straight with a ball-peen hammer. As I recall, we never ever used any sort of sealant on any brand of trans.