i have been into a lot of GMC engines but I have never seen anything like it. I have seen crank failures with a bad vibration damper. And I have never seen an engine without one. What happened with your catastrophic failure? I would be afraid to run a setup like this because I have seen crank failures caused by a bad vibration damper. I would put a vibration damper on it.
I agree with most of this above. Though there are some engines with out a damper / balancer though, VW aircooled is one everyone knows.
