Volvo Penta Bell Housing Flywheel Cover. For 4 Cylinder b16 / b18 (BB70 Volvo Penta) engines as well as the aquamatic 100 outdrive and transdom shield. In great condition, the bearings are still in great shape and housing is in great shape. Shaft has 6 spines for the AQ 100 Upper Gear Unit. The inside shaft for the engine coupler (flex plate) has 10 splines.