Thrust coupling (on gearbox) w/keyway

The pilot joint is located on the gearbox. Until November 88, the part that fits into the gearbox was 37 mm in diameter. At that time, a simpler seal had to be used, which did not seal as well. Therefore, the factory switched to 35 mm, which allowed for a seal with a spring. (The slightly thin material left over the keyway was a result of this). If you have to switch from old to new pilot joints, the movable coupling must also be replaced (5310001-81) since it has 4 claws and not 2 as before.