I am looking at buying a 97 420AC with 7.4's. One engine reportedly had loose bolts on the engine coupler and it wallowed out the factory holes and the the bolts eventually sheered. The current owner had new holes drilled and reinstalled the original coupler. That engine now has vibration issues. I think a new coupling is in order. The boat appears to have tides dripless seals. Can a new coupling be installed with the boat in the water?