Complete Sidewinder kits contain dynamically balanced flywheel assembly Includes rods and main shafts, cylinders and pistons- fit and ready to install with head and base gaskets S&S adjustable push rods are also included Stock cases and heads must be bored to accept the larger 3-5/8" bore cylinders Stock cases must be cleared for the crank pin nut S&S manifold must me purchased due to the increased cylinder length 4-3/4" stroke