troubleshooting rear differential
1989 XLT lariat 4+4. put the truck in first, let out clutch, felt a pop, like a cable not like thick metal. truck won't move. put it in rev. let out clutch, no go. in 2WD clutch in or out, I can run through all gears to no affect. lock front hubs and drives fine in 4WD. ( i'm sure the back is free-spinning) put it back in 2WD, put it in 1st. let out clutch, nowhere. Got out (still running in 1st) rear drive shaft spinning all the way into the rear diff. Am I going to have to/ or should I replace the whole rear end or could I be missing something smaller?