Cobra SX Engine Coupler Sierra 18-21751 Sierra Cobra SX Engine Coupler 18-21751 Enginr coupler connects OMC & Volvo Penta GM engines to stern drives. Fits OMC 2.5L engines from 1986 Fits OMC 3.0L engines from 1986 to 1990 Fits OMC 4.3L, 5.0L, and 5.7L engines from1986 with KW and KWB model suffix only Fits OMC and Volvo Penta 7.4L engines from 1990 to 1998 and 8.2L engines from 1992 to 1993, 1998 Replaces OMC 3853962, 983902, and 986338 Replaces Volvo Penta 3853962, 983902, and 986338