I replaced my old Volvo sail drive with a Beta 25 and Seaprop 60 sail drive. The Volvo saildrive had a 3 inch extension so the output shaft had enough clearance to swing a 16 inch prop. The Seaprop 60 only gives me 7 inches of clearance so I can only swing a 13 inch prop ( which are no longer available ). Does Seaprop make extensions so I can use a larger prop?