[VetteVet]

What I do is take the engine pulley off and put two longer bolts in the holes where the engine pulley mount holes were. Then I take a large screwdriver and put it under one of the bolts and over the other one. That gives me a way to keep the balancer from turning and you don't have to worry about the outer ring on the balancer turning if you're holding it with a chain or strap wrench.
Actually if I can get to it I use my air impact wrench on the bolt but in case an impact isn't available the other way works great.