I have used ATI "Super Damper"s on my 428s and 427 for decades, ever since NHRA started mandating SFI certified balancers on cars running 10.99 or quicker ETs, probably in the late 80s or early 90s.. For whatever reason, the ATI balancers have the timing marks of 6 or 7 degrees, which is very easy to correct with a minor modification to the original timing pointer. And the mounting pattern for the crank pulley (s) requires slightly elongating of the pulley holes to align . If you were to take a walk thru the pits at a dragstrip, you will find that the vast majority of the engines have ATI balancers, and that virtually none use a FluidDamper , TCI Rattler, or anything else.