I'm in the same boat... transmission just started leaking over night, got new gasket but after pulling the pan off, it looks like its leaking from the gasket with the transfer case...
Has anyone actually sorted this out yet?

 

Got this sorted today.
Leaking from gasket where the 4x4 adapter housing meets the rear of the transmission.
Remove rear driveshaft, transfer case, cross member, adapter housing.
Replace the following from RockAuto:
Tranny to Adapter Housing gasket: PIONEER 749121
Adapter Housing to Transfer Case gasket: PIONEER 749289
Transfer case input shaft seal (optional but as transfer case is out, why not): TIMKEN 710652
Both gaskets are paper ones, so I will be coating them both with a light film of RTV.

 

I know the discussion was old but did you ever found a fix for it. Mine has the same leak as your and I changed the filter and gasket but it didn't fix

 

I would advise against the RTV use in an automatic transmission. The paper itself works just fine....until it gets cooked and hard.

 

Does anyone has the same leak as nitro3421 and found out where the leak came from?

 

Does anyone have a DYI on replacing these gaskets and seal. I have a 2008 F250 4WD with 5R110W transmission and it leaks at the same place. I am not sure if this transmission has the same part number as Steelandspeed mentioned above. Any inputs are highly appreciated