Great thread with lots of pictures! Thanks for posting so much.
In an earlier post about heat getting in the cabin: I put a flashlight in the cab, turned out all the lights in the garage, and crawled under the 40 and looked for light leaking through. Amazing how many holes I had in the firewall and tranny cover. Sealing them really helped.
Man, so glad you posted this. It reminded me to order more strip caulk, aka dumb dumb, to seal up all the holes.