Figured id share my garbage..

You sure the diff was properly set up? That's a bit of magic to me. One of the few things I tend to send to a shop that I trust.
It was setup by someone that’s been doing it for about 100 years. Did a ton of other local cars. I won’t say it was or wasn’t properly set up as anything can happen and I’m certainly not a diff guy.

Hows the ring gear look? For it to stop turning one wheel it would have to have lost the splines on the axle or spool. I have seen axles not have hardly any engagement and then break when a good amount of power is applied.

I’ll grab a photo of the ring gear here in a bit. All teeth and splines were accounted for when I looked. I’m scratching my head on this one.