I recently purchased a 81 Catalina 30. I have multiple questions. The engine, an Atomic 4 was rebuilt and runs great except in reverse. It works in reverse, it moves but the transmission sounds like it's about to have a coronary. Is that normal due to the mechanics of reverse? I need to replace the holding tanking due to a leak. Any body out there found a suitable replacement that doesn't require sawing the boat up? Thanks