[THEFERMANATOR]

I would be checking the splines of your prop shaft for damage. The prop must slide all the way forward to the thrust washer and on far enough so that the prop slides just inside the gear case to seal exhaust gasses. Some props do use a different washer arrangement to hold them on, but to my knowledge OMC only used 1 style prop for the V6 gear case(there was a thrust washer change in 91, but this didn't effect the prop).