Lower unit Complete Replaces: Mercruiser® Alpha One Gen II series STD Rotation $795.00 Counter Rotation $995.00 Call toll free to order 888-567-8448 Lower unit Complete: Replaces: 1973-1991 Mercruiser® R/MR/Alpha One series. STD Rotation $695.00 Counter Rotation $895.00 Call toll free to order 888-567-8448 PRODUCT BREAKDOWN Lower Gears Water Pump Assembly Oil Seals and Gaskets Zinc Parts Bearings Bearing Carrier Shafts All bearing carriers are made of die-cast anodized aluminum.