Cams for 00-06 Twin Cam are for use with stock splined drive gears; for installation on 99 Twin Cam motors you must purchase splined outer drive sprocket; S&S recommends that Andrews 4340 steel drive sprocket PART #DS-199175 be used
Cams for 06 Dyna and 07-10 Twin Cam are for use with models with hydraulic tensioner chaindrive system; cams 510C and 551C are bolt-in applications, all others require high-lift valve springs