These components are produced specifically for the Quicksilver aircraft that have the engine mounted in the middle of the root tube. Early single place and two place aircraft used a 4 belt system and the pulley diameters were 3″ and 6″. These pulleys were “clamped” to the drive shaft and prop shaft. Sometime around 1988 an updated system was introduced that utilized a 5 belt system and the diameters were 3″ and 8″. These pullies attach to their respective shaft in a much more secure attachment. The main issues with this belt drive system is the fact that the two shafts must be maintained in a parallel configuration and the belt tension is critical. Improper alignment will result in unequel load on all the belts. Too much belt tension will result in bearing failure. To loose and the lower pulley will slip and eventually damage the surface of the pully.