Bought a Gheenoe last year with a Suzuki DT6 on it. I think it's an '85 cause that's what the boats registered as, but there's no letters in my serial number. I would like to change the impellar and gear lube but having a tough time finding info or manual for it. What gear lube is recommended for this year? Is the impellar change pretty straight forward on this year? The stamped serial number is 00601-612701.