This unique design damper is for use on externally balanced small block Chevy engines. This would typically include 383 and 400 c.i.d assemblies. Only a few damper manufacturers offer a small 6-3/4" damper for these engines and those dampers are usually very expensive. This model, like all of our dampers and other products, are very high quality products at very affordable prices. Note that although this model damper features a bolt-in counterweight, the damper cannot be used without the weight. Due to the windows cut in the front face of the damper, if the counterweight is removed, the damper is still not a neutral balance damper. If you need a neutral balance 6-3/4" damper, use our ARC 8035060 model.