[Michael C Henry]

I have the OEM 427 harmonic balancer It seems to have a single grove pulley built into it. The three bolt holes for accesssory pullies ,the threads start flush It lookks like one peice .I picked up a old damper from the machinist .The two row pulley was a tight fit on the center but you could tell it was a seperate piece from the main body of the damper and had three holes but you could tell that the threads were in the damper behind it and bolted thrugh the pullies.I do not think anything on thease two dampers will mix.