I grenaded my slant 6

Could be oil supply, could be harmonics, could be shaft torsion, could be block flex....what else...?
Poor lube, assy., or components, on a stock/mild Slanty..period...none of those "tech mysteries". Otherwise the failure rate would be well over 50% for an engineering oversight that "deadly"....go to any dealer and look at what's in the scrap pile, or re-boxed/crated waiting to get sent back, .....from 229 V-6 Chebby disasters as shortened 305's in the late '70's-early '80's, said 305's eating exhaust lobes(4100 Caddys too), to modern Hy Theta engines that now have a lifetime warr extension, pattern failures due to mfr processes/materials or design/engineering show up quickly & often. The latter of this simply is not the case,....