OMC Sea Drives were marketed in the 1980's and did not perform as well as conventional outboards.They were basically Evinrude motors mounted to a unique hydraulicly activated bracket for trim and tilt. They came in V4 and V6 models. I would stay away from them because they are obsolete. But if push comes to shove, you can take a powerhead or lower unit from a mid-late 80's Evinrude or Johnson outboard and replace the Sea Drive parts with them. Even the wiring harness is a plug in. More work than it's worth these days.