A guy recently gave me a 1977 stingray w/mercruiser 140. I removed vent and fill plug in lower unit and nothing but dirty water poured out. Prop housing has about a 4" crack in it, from the end inward. I am going to disassemble and see what goes. Is this crack repairable or will I need a new lower housing? I don't know if he hit something hard or what. Prop looks good and all. I now know why he gave it to me!