TH350 squeal grind screech after fluid change

[scottdburnett]

My 72 C10 sat over the winter and this spring wouldn't shift into gear after starting up. Realized that I must have had enough fluid leak out to prevent shifting.
I jacked it up and drained the fluid, less than a quart, dark and dirty. As recommended by others on 67-72, I had to jack up the tranny a little bit under the flywheel cover to get the bolts behind the crossmemeber, then dropped the pan, cleaned the pan, installed a new filter and gasket. Reinstalled everything w proper bolt torques and added 4 quarts of fluid.
Started it up and there was instant high pitched squeal of grinding metal.

Shut down, cycled through the gears several times and re-started. Sounded better in park but still there was a new squeal, let it run to warm then checked the fluid level. It was a little high so I drained some fluid out.
Now the squeal still present but shifting into reverse or drive intensifies the grinding squeal.

What have I gotten myself into?
Did jacking up the transmission mess with the flywheel?

Sound in Park:
https://youtu.be/8VVPz4CnzZU

Sound when shifting to Reverse:
https://youtu.be/fanyF1P2E_o