Sierra 18-6028 Zinc Anode Sierra aftermarket engine parts are designed to meet or exceed OEM requirements. For use with OMC Stern Drives or Volvo Penta engines. The 18-6028 anode is made out of zinc and should be used in saltwater applications only. Fits Gearcases 2.3L 1987-90 Gearcases 2.63.54.6L 1989 Gearcases 3.04.35.05.8L 1987-93 Gearcases 5.7L 1987-92 Gearcases 7.4L 1987-88 Interchangeable with GLM 12774 OMC Stern Drive 3853818 3855140 3855411 984513 Volvo Penta 3854866 3855411 California R