Mercury - Quicksilver 821629T1 Aluminum Drive Shaft Housing Anode MerCruiser Alpha One Gen II Sterndrives 821629T1. Overview. Corrosion can quietly wear down your drive long before you notice it. The Mercury 821629T1 Aluminum Drive Shaft Housing Anode protects your MerCruiser Alpha One Gen II sterndrive from galvanic corrosion in both fresh and saltwater. It's a small, easy-to-replace part that saves you from expensive repairs down the road.. This OEM anode is made from marine-grade aluminum tha