OEM balancers will not hold up well under extended high RPM conditions, or at least they say they don't. I know many that run them with no problems. Will and Kelly Mclearen( Kelly is the driver ) run a rebuilt OEM balancer on there '63 Falcon with a Turbocharged 250 I6, which does 11.85 in the 1/4 mile, and races regularly. for my Turbocharged 200 I6 '67 Falcon, I bought a new factory reproduction OEM balancer ( it's a Scott Drake reproduction ), grantid, I do not know how it will hold up yet, cause it's not running yet, but I'm shure it will do fine.