Hello I tried to use the search function but couldn't find what I was looking for so I am sorry if this is a topic that is discussed frequently. I was with a buddy in a 1988 Gambler bass boat on the river yesterday. The motor is a Pro V 150G. We launched and idled out to the river for a ways letting it warm up. The boat ran great we hit lower 60's in it and we drove around for about 20 minutes or so looking for a place to fish. We headed back up river cruising at about 35 to 40 on plane and the boat just quit and wouldn't go under load. We heard a slight grinding and immediately pulled back on the throttle. We stopped and looked at what we could in the water and the motor was still running good. We tried to take back off and every time we tried to give it gas it wouldn't go. To me it sounded like when a clutch in a car is about to go out and free spins. The motor had tons of power and didn't sound any different than normal. We had to idle back and made safely to the dock with the motor. I checked and the motor will go into reverse and run and also will stay in gear. It didn't slip out just free spun. I looked it over and the motor when put into drive you can't turn it with out turning the flywheel on the motor as well. The motor was still spitting water and no alarms sounded and the guages all showed the same. The fluid in the lower unit was changed in the fall and hadn't been out since. We drained the lowere unit when we got home looking to find some chunks of metal and nothing. The oil looked like the same when it was put in and didn't look chalky. If anyone has any thoughts on what it could be that would be appreciated.