I need help! Recently purchased 1975 cobalt dv19. Made some minor repairs. Took the boat out for a test run up and down the lake, and everything was fine. Went back out a few hours later, again everything was good, then all of a sudden something breaks in the outdrive. It now appears that something give between the engine and the ballgear driveshaft. I'm told there is a coupler there. I own a factory omc service manual, but can't find it mentioned anywhere. I've looked at all the parts diagrams too, and can't find it there either. Any info would help. thanks