Originally Posted by Mav
Hi thanks for getting back to me. The engine is an old but still reliable Ford 2700 from the '50s. 4 cylinder and 85hp. Shaft is 1 1/2" and turns a 3 blade LH 22x18 prop. Look forward to hearing back. Boat is in Honolulu.
The Most common model in the 2700 series is the Ford 2701E also known as the 240 - its HP is rated at differing RPM is between 70 and 74 HP.
Rebuild kits are still available (If necessary) at around $800.00 US containing Pistons, Rings,Main bearings, Conrod bearings, Thrust washers,Full gasket set including front and rear seals.
As it is most unlikely that you will be able to either replace the Paragon or repair it satisfactorily. The best bet is to find a suitable current day model that will replace easily. A challenge will be to find a way of "closing the gap" Your 17" (430mm) long Paragon, is a fair bit longer than the average modern gearbox of only 250mm.
Need to check that measurement again. It may be necessary to introduce a steel coupling between the new gearbox's output flange and the existing propshaft coupling - not impossible.
The other issue is to match as near as possible the Paragon's reduction of 3:1.
A 2.8:1 is about the greatest one in the size suitable for the 2071E. The ones that come to mind are the ZF 15, The TM345 from Technodrive And the PRM 150. A used box in good nick is worth considering.