Sierra 18-21752-1 Engine Coupler for OMC, VolvoSierra replacement engine coupler for OMC and Volvo Penta engines. Sierra aftermarket parts are manufactured to meet or exceed OEM requirements. 17 Splines; Fits: 4.3L (1986-1998); 5.0L (1986-1988, 1998); 5.7 (1986-1992, 1994, 1996-1998); Interchangeable With: OMC Stern Drive; 984290; 986120; 3853917; 3858437; Volvo Penta; 3858437; 3858437-1;