While waiting for my new converter and flexplate to arrive, I noticed something weird. The balancer is a 427 type, not the 454 type. The motor is is a crate LS6 with the correct block numbers on the front pad and the flexplate is correct for a 454(weighted, externally balanced 168 tooth) I have not had the engine out of the car yet so I don't know for sure if it's been modified. The motor runs strong and has no vibrations what-so-ever except at idle of course. Any one have an idea? Thanks.

Only if the 454 is internally balanced like a 427!!

Otherwise, run your fingers up inside the back of the balancer while you are laying on the ground and check for the usual 454 balancer feel if your motor is still in the car..

A 454 balancer will have a raised place in the inner back of it whereas the other BB balancers won't..

pdq67

I've heard of Eagle doing this, but not GM. It may not be wrong, but you should check.