I recently installed a rebuilt engine and replaced the motor mounts. I realigned the shaft/transmission coupling. I had the boat (Catalina 25 WK) on the trailer. I have since put 6 hours on the engine and the vibration increased. Last week the boat was in the water so decided to re-look at the alignment of the shaft/transmission coupling. I could not get everything to align correctly. I then took a dial indicator to check the run out of the parts. The shaft and its coupling were within two thousands. The transmission coupling ears were out to each other over thirty thousands fore and aft. I built spacers to compensate for the mis-alignment and spent a couple of hours re-aligning. It is now smoother that it has ever been. Was worth the time and effort.