Abstract: A marine stern drive (10) has an engine output coupler with a coupler hub (56) having an axially splined opening (58) receiving the forward splined end (28) of the output drive shaft (24). The coupler hub has a pair of axial channel passages (60, 62) therein spaced radially outwardly of the splines (58), radial channel passages (64-69) extending radially inwardly from the axial channel passages, and inner circumferential channel passages (70, 72, 74) extending circumferentially around the axial splined opening in the coupler hub and intersecting the splines (59), A grease fitting (76) on the coupler hub communicates with one of the axial channel passages such that grease introduced at the fitting flows through the axial channel passages, through the radial channel passages, and through the circumferential channel passages, to lubricate the splines of the coupler hub and the output drive shaft.