Im looking at possibly buying a new engine block for my excavator, it has a yanmar engine in it, and i came across basically a complete shortblock from friday parts for pretty cheap. Its labeled as new aftermarket. They are a Chinese based company selling used and aftermarket parts. I wouldn't be worried if it was just a few parts, but for a whole block and rotating assembly im a little unsure about. Anyways if anyone has experience with them let me know.
I actually purchased a hydraulic pump from FridayParts, which is also a pretty precise and critical component. Like you, I was a bit concerned about the quality at first, but I was pleasantly surprised. I saved over $5,000, and the pump has been working perfectly for two years now.