I agree. I see them in the dirt at swap meets and the want 400-600 calling it a good core.

I have them "LOOK" real good and howl when run.

so it is rolling the dice. but there are good used ones out there and depends on how bad you want one.

I swapped all my 80s trucks over to 8 3/4-green bearing for fast gear change. but my 74-489/3.91sg is howling, my 72-741/2.76 open roars, my 67-742/3.23 open is good shape.
not bad enough to make me stop driving them and they all have well over 300,000 miles...still going.

at the 1200$ price for a new rebuild or a 600$ known good one the best bang for the buck would be a call to Dr. Diff for any 8 3/4 needs.

used to new he has great service with best pricing around.

send him yours or buy/exchange what ever you need.