This is the first old style u-joint I have come across that is not worn out. It is keyed to the driveshaft just like all of the newer bikes. Charlie’s patent drawing shows a splined connection to the driveshaft. The rubber boots are intact and it has a grease fitting that is accessible while installed in the bike. It has a 1/4″ split pin instead of 3/16″ like the MK1s have.