Rear Differential locked at 315,000... fix or sell as-is??

In all of my years of working on cars and trucks, the number of rear differentials I've seen fail and lock up is exactly zero. (I've seen differential failures, but they didn't lock up.) The number of rear brakes I've seen lock up? That's a waaay larger number. Glad you finally found a decent mechanic.

 

For sure, the mechanic is going to look at the AC too that stopped working after the dealer did the frame recall (dealer then wanted $500 to fix it!). After that, I think it's just fixing or replacing the factory cd player that stopped working. It's still a great truck.