I have a 1997 Volvo penta 350 with a Sx-C1 duo prop out drive - I recently replaced engine and top half of out drive, as well as the gimble bearing and oil seal. Once I reinstalled and aligned everything I tested on muffs and I get a nasty vibration and rattling sound from the gimble bearing area between 2000 rpm and 2500 rpm. When I remove the out drive the vibration/rattle is gone. Out drive was just rebuilt and new u joints were installed in the shaft. I have also inserted the alignment tool and tested and vibration comes back. I am currently working on replacing the coupler and installing a new gimble bearing to see if that solves the issue, however I am curious if anyone has seen this before