Cast from A356 T-6 heat-treated aluminum alloyCases are available for 31/2" stock and 35/8" big bore motors for any stroke up to and including 5" and most stock length connecting rodsMachined to accept an oil filter assembly that mounts on the front of stock motor casesAll races are line-honed and breather cavity is precision-machined to optimize breather timing for maximum oil scavengingAdditional parts include crankcase bolts, washers and nuts, cylinder mounting studs, timing hole plug, magnetic drain plug, assorted breather and oil line fittings, oil screen, spring and plug, sprocket shaft Timken® bearing assembly and oil seal, pinion shaft main bearing race, cam needle bearing assembly, oil pump drive shaft bushing and installation instructionsMade in the U.S.A.