Manual transmission leak source?

4.0L manual trans - 60k miles. Finally poked my head under the truck to see where my gear oil puddles are coming from. It looks like it's leaking right from fill plug on the trans. However, there is a large piece of plastic right above the fill plug that sandwiches foam between it and the trans. The foam is soaked. Is the gear oil wicking it's way up into the foam, or is the source of the leak higher up? Is this a common leak? I'm hoping it's just the fill plug, but there is oil above it, so I'm not sure.

 

I forgot to ask: What is that foam and plastic sandwich for, anyway? It doesn't look like a heat shield setup, it's almost like it's protecting something underneath? Edit: Found it in the awesome online FSM's. "MANUAL TRANSMISSION CASE COVER SUB-ASSEMBLY" Seems like it serves no purpose, wtf.

I think I'll get some gear oil, my handy gear oil pump, and a new crush washer and see if it leaks again.

 

Hey I recognize this thread is 5+ years old and nobody replied, But I've got the exact same issue except I'm pretty sure the source of the leak is the soaked foam. I've got a 2005 with the 4.0L/6spd manual. started leaking about 4 months back. Not a lot but it is not going away

Anyone run into this before?