These dampers are manufactured to match the dimensions of the stock early (1963-'69) small block Ford dampers.
The outside diameter and the thickness are the same. The counterbalance weight matches the stock 28 ounce inches and the overall balance specifications are held tighter than the original O.E. tolerances.
The dampers have both the early 3-bolt accessory pulley bolt pattern and the later 4-bolt as well. This will allow the use of late model serpentine drive systems on early engines if desired.
The counterweight for this damper is removeable, so if you want to build a neutral balance engine, you can use this damper by simply removing the bolt-in counterweight on the back of the damper.