Fits with OEM flywheels. Sprocket shaft does not have a keyway. Taper is 8-1/2°. Biggest part of taper is approx. 1.400". Shaft is 4.262" long from bearing shoulder to end of smalll thread. Use 24017-80 JIMS nut (MCS 978257) on flywheel side and use 24003-55 nut (MCS 518000) on sprocket side. Note: Use MCS 502616 JIMS shaft for all 70-99 aftermarket flywheels that have a keyway and 6° taper. JIMS shafts are precision machined in Camarillo; California from a special order steel. Each and every part is thoroughly inspected and after heat treating all threads go through a special process to make them withstand greater torque stress. All shafts are ground to a 16 micron finish or better; unless specified otherwise. All ground diameters are concentric to well within .0003"; making truing and rebuilding quicker and with less effort.