96 4x4 cracked case on 4L80E Tranny

[Old Suburban]

Hey guys, I'm into my second 4L80E tranny with this truck....shop fixed last problem but failed to diagnose the real culprit (out of balance drive shaft) oh but it gets better, I'm now out of warranty! and have the same problem cracked transmission case.

Truck is in decent shape with #180k on it (lots of little items to fix radiatior leak, waterpump leak) I'm seaching for another tranny if anyone out there has a used one laying around, or one to be rebuilt. Don't want to spend the $1,600 to get a new case/tranny installed (includes balancing drive shaft). Thought I might find a used one and do it myself.

Thanks for the input
John