Ouch. My 904 looked about like that when it decided to stop reversing.
If I were you, I'd just go ahead and put the pan back on and start pulling the trans. I tried to leave mine in-place while slowly taking more apart hoping I didn't need to rebuild it.. I should have known better. My uncle is a transmission mechanic and he would always say "as soon as an auto does something it shouldn't, it's time to pull it."
It's not as bad as it sounds so long as there's not major damage to hard parts. I think my kit cost a little over $200... But I don't remember if I replaced the bands or not.
