A904 Woes.. not working right..

The first clutch out is called the front clutch, go figure but everybody I know calls it the High Drum, cuz that's the clutch that makes high gear.
The second one out, the one you found all burned up, Mopar calls the rear clutch, but again, everybody I know calls it the Forward clutch, because it causes the car to go forward, lol. Obviously yours is toasted.
That aluminum piece you unbolted from the back, that you found all messed up; I think it's called the governor support, but really, it supports the L/R drum, which supports the sprague inner race. Look inside the drum and it'll look similar. Since it's aluminum welded to steel, if the part is otherwise reuseable, you can remove it with weak hydrochloric acid, sold in hardware stores as muriatic acid. Unfortunately, that stuff is only 5%, so it's pretty slow.