The only good way I have found to chase leaks is to have the car on jack stands or a lift if one has access, clean the grease and or oil off the offending part, in this case the transmission then start the car up and watch to see where it leaks from, I have in the past sneaked into the local quarter/two dollar car wash with a floor jack, stands and a piece of heavy cardboard carefully pressure washed transmissions before, then took it home and put it on stands and finished the cleaning with brake clean or some similar solvent and wipe with rags, no real easy way to do it or anything specific to look at as there are several areas that can leak, front seal, cooler lines, pan gasket, shift control, rear seal and I've also seen them blow oil out of the vent from excessive internal pressure, If you use good heavy duty jack stands on a level, hard surface and put a pair under the rear axle as to load the rear suspension and a pair under the frame in the front you can actually carefully run the car through the gears as well but not while you're under it, clean it, run it, look for leaks, repeat till you find your leak, Good Luck, KillerDave