Help Identifying Leak Under MH?

Thanks for the quick replies, guys, appreciate it. Not easy to get under (bad back), but did it, wiped area, and guess I missed an important "clue" last I looked. Pan is stamped "Allison" and white paper test shows red fluid. Don't I feel the fool. When I first found the leak it was a warm engine after returning from camping in MS. I immediately checked fluids including trans which was in the correct "Hot Eng" range of dipstick making me think other than trans fluid leak.

Midnightsadie, thanks for the Mobil Tech suggestion. Before I call my guy in, does this pan have a gasket that's DIY to replace? Anyone ever done it? Any tips? Thanks again.