'76 C10 Crank Pulley wobble and squeal EQUALS?

[Fhunter1]

I have seen a balancer fail at the elastomer bond between the other ring and inner hub but that just had a horrible rattle.

I would carefully check the balancer as a starting point to be sure the elastomer hasn't failed and allowed the outer ring to move.

Next I would check the run out of the crank nose as suggested above. The video linked below shows how to do it on a shaft , but you get the idea.

https://www.youtube.com/watch?v=s-UG2CZ8VMM

Let us know what you find.