... why oh why did GM think it was a good idea to put an elastomeric pully accessory drive on this block?
DANG that thing is loud when it's broken!

You give me hope that that will help mine too. I could see the scars where it was twisting the pulley and hitting the center section.

the replacement from napa came with woodruf keys... does that mean the banging pully may have sheared the keys on the balancer? should I bite the bullet and pull the balancer, and replace the keys too?

... why oh why did GM think it was a good idea to put an elastomeric pully accessory drive on this block?
DANG that thing is loud when it's broken!They were trying to prevent the belt pulsation that all diesels have-unfortunately the rubber cracks & fails. I don't think a serpentine belt would last long w/a rigid pulley, the v-belts on the old/pre-'85 6.2s would flap so hard they would cut the upper radiator hose, that's why many had pieces of metal attached to them. I doubt if you damaged your balancer-but if the rubber is cracked or coming out, it should be replaced anyway.

nahh, the balancer looks fine. I'll leave it for now.
can't believe how much changing that pulley makes on the behavior of the truck!