Ford Big Block 429-460 6.7" Damper. These dampers feature the stock 3/16 keyway plus a 1/4" keyway 180 degree from the stock one. This allows the damper to fit aftermarket dual keyway crankshafts. Note that while these engines are classed as an externally balanced engine, the counterweight is a separate (Ford #M-6359-D460) part.
