Originally Posted by matLT1

I wouldn't think it is due to your flexplate swap. The reason I say this is because these engines are internally balanced, meaning the flywheel and balancer don't have a role in balancing the crank. Unlike some of the older engines like 454's and 400's that were externally balanced that did rely on the flywheel and balancer. I would check the flywheel to make sure it isn't warped, some companies will ship them that way once in a while. Also, did you use an alignment tool when you installed you clutch? And does it vibrate when you rev it while the car is parked or is this only while you are driving?

Originally Posted by matLT1

I wouldn't think it is due to your flexplate swap. The reason I say this is because these engines are internally balanced, meaning the flywheel and balancer don't have a role in balancing the crank. Unlike some of the older engines like 454's and 400's that were externally balanced that did rely on the flywheel and balancer. I would check the flywheel to make sure it isn't warped, some companies will ship them that way once in a while. Also, did you use an alignment tool when you installed you clutch? And does it vibrate when you rev it while the car is parked or is this only while you are driving?