Heavy Duty S&S connecting rod assemblies have a stronger than stock construction. Manufactured from drop forged 4140 chrome moly steel. Designed to be used as heavy duty replacements for stock or modified engines. Complete with crankpin; crankpin nuts; woodruff key; cages and rollers. Ready to install. Note: With wristpin bushing installed; reamed to L81-83 Shovelhead OEM .791" diameter. For use in 84-99 Evo Big Twin models wristpin bushing must be reamed to OEM .792" OEM size. Note: See 508664 for identical connecting rod assembly with wristpin bushing reamed to 84-99 Evo B.T. OEM .792" diameter. Note: Comes with steel cages. Note: S&S rods are clearanced for strokes up to and including 5". The connecting rod assemblies come complete with crankpin; nuts and with a 17 roller alloy type cage crankpin bearing set. All S&S connecting rods are a somewhat heavier than stock due to a beefier construction. Flywheel rebalancing is recommended. Rebalancing may be extra work; but S&S decided not to sacrifice rod strength for convenience''s sake. All rod lengths are same as stock (7.440" center to center for Big Twin models).