65 Barracuda A 904LA trans. leakage problem

It seems obvious, but is this where all of that trans fluid is leaking from?

Probably but Not necessarily. I would thoroughly clean everything then you would have a better chance of locating the leak. Other possibilities include the pan gasket, the where the shifter cable enters the transmission, the kickdown area, a bad O Ring on the speedometer pinion housing and least likely (but possible) a crack in the torque converter where it enters the pump (was source of my leak on an Aspen I owned).