Hello All, I have a 66 hardtop with a 68 302 that I rebuilt. Machine shop balanced the aftermarket balancer, crank, rods and flexplate but I now have rhythmic vibration at idle and when driving. I checked the flexplate for runout and it runs true all the way around EXCEPT at the counterweight, where it jumps to .030" runout. My first thought was warpage from the heat of the weld, but they would have caught that when balancing. I've since read the description of a Scott Drake flexplate (mine is not) and it says it has counterweights on both sides. My question is; could the counterweight on the other side be against the TC and thus causing the runout? Is there a recess in the TC for this reason? Any help is much appreciated, thanks.