Broken pin in differential

I started having problems with the rear wheels locking up on my roadrunner. The shop called me and said a pin broke in my differential and is causing the brakes to stick on one side. Anyone ever heard or dealt with this? . Before it was in the shop it locked up in the driveway. I put it in neutral and we couldn't even push it. Eventually we go it moving but it kept happening.

They are talking about the cross pin, its what the spiders run on