You're talking apples and oranges here. The forementioned engines are all Detroit Diesels made by GM. The OP is talking about a GreyMarine 4-112 which is a marinized Continental block used in various fork lifts, gen sets and such. Armed with the knowlege of it's true identity I was able to get piston/ring set, all engine gaskets, main and rod bearings etc. and did a complete rebuild
on mine for about $800 including turning the crank and resurfacing the cam. Now depending on which gear
box you have hung on the thing, you will be looking for a new seal for that, not the engine itself. Mine was a mechanical Paragon gear
, and I was able to replace all the seals
and bearings except one that was a peculiar to Paragon and no longer available. But you can still buy the balls and replace them in the races, and that bearing was only used in reverse anyway. I used it for a year and replaced it with a diesel
. It's for sale
if anyone is interested.....