I'm new so bear w/ me. I've got a '84 Carrera w/ twin 454 at about 475HP so I'm told by previous owner. The outdrives are '83 or '84 Merc. I do know they have an eyelet on top of the upper units. anyways the problem is I was on the lake today for about an hour and a half. No problems at first; later one of the units felt like it was trying to neutral. after heading back to land it stopped I thought. A 'lil I went from half throttle to full throttle rather quickly I lost one of the units. It will not shift into rev. or drive. The fluids are O.K.; the temps didn't rise or nothing. What could be the problem? Other forums talked about couplers Is that it? Any help would be greatly appreciated!