Looking for 700R4 expert

[71C10Guy]

I have a '71 C10 with a 700R4 in it. A year ago I was pulling out a side area of my property and ran a bit into a berm, gunned it to get up it a bit so i could back out, and all of the sudden all gears just went out. The parking prawl engaged, and i went underneath and shifted it by hand to be sure that it was actually shifting. But reverse, 1,2,3,D nothing would work. Checked fluid while it was running and it was full. No burnt fluid, but when pulling the pan the entire thing had about 1/16- 1/8th of an inch of metal slivers in the pan. The trans was rebuilt about 2 1/2 years before this. I'm just wondering if anyone can point me in a good direction to get started diagnosing?

Thank you!