OC46 with Hercules diesel - parts?

I'm not new to diesels, crawlers, or Cletracs - but have never owned or worked on a Hercules diesel before. Are engine parts still easily found?

All I know is this. The past owner converted it from gas to diesel years ago. Where he got the engine, I don't know - but I assume from another OC4 or OC46. It's a Hercules diesel, that's for sure. He used it for years after installing the diesel. A few years back he was having trouble with it - lost his oil pressure. So, he pulled it apart, put new bearings into it that he bought at Zimmermnans - and it seems still had no oil pressure. He died before fixing it. Looks like he was getting ready to pull the engine out when he died. So, it sat for a few years in storage - and now I bought it from the family. It's half apart - and I'm not even sure of the order of problems. I.e. - I'm not sure if he lost oil pressure first - and then put in new rod and main bearings - or put the bearings in and THEN lost oil pressure? His son - who is here for a week trying to clean up the estate - thinks he lost his oil pressure one morning all-of-a-sudden during a cold start and is thinking maybe the oil-pump drive broke? I have no idea - so I guess I'll find out later. Engine does still turn over. Loader has an Oliver tag on it - reads OC46 # 3838. I assume that's the loader ser. number - not the tractor.
Has a four-speed trans plus a reverser - all parts seem to be there. Standard differential steering. Paid $500 - for that, I couldn't pass it up - that's just about what it would bring in scrap. Tracks and rollers look good. One new sprocket on it. Also, a 50" bucket plus a tree-pulling contraption that goes on in place of the bucket. We'll see. Last thing I need is another crawler or project - but just couldn't pass it up at that price.