I recently put a Bravo 1 lower prop shaft in, ran the boat for a 1/2 hour and suddenly got what I thought was a outdrive noise at higher rpms, lifted the hatch and sounded a little like exhaust. Removed the outdrive resealed , checked bearings, OK, have to check the coupler. Has anyone had a couple problem like this? It does have a big block 454. The Gimble is ok and alinement is right on, spines are good too.