Rear main vs tranny input seal leak

[Texasdoc]

I have an increasing amount of oil dripping from my engine plate. T5z mated to 408w. At first I suspected the rear main seal. I tore everything on the back of the motor apart. Tranny off, clutch off, flywheel off, then oil pan, 5th main cap, and then replaced rear main seal.

I examined the flywheel and clutch, no oil on them that I could see. Oil plugs on the back wall are dry. Nothing dripping down from the intake. Heads and valve covers are dry. I did notice that the inside of the bell housing was wet with oil - but it didn't register at the time.

I reassembled everything but still have the same leak - from the engine plate. I'm now thinking that it may have been the tranny the whole time. Any suggested way to test the tranny input shaft seal, or just rip it out and replace it anyway?

I will someday get a TKO600 for this car. I just had a dyno session tuning the EFI. 407hp, 489tq at the wheels. I know this T5 cannot handle that much power. Since I never abuse the tranny, I was hoping to delay that for a little. My other vacuum (Jeep) has gotten lots of new parts lately. The spousal unit is starting to glare at me with those eyes....