Lets stop here, and start over.
First, just because the hour meter says 5 hours, is not grounds to think the engine and set only has 5 hours on it. It also doesn't mean it only has 5 hours on it since "rebuild". Gen sets do not get rebuilt. They do go through "reset", or Tier 2 Reset. I think I can post the work requirements for "Tier 2 Reset" if you all are interested in what gets replaced/checked during the "Reset. But a "Reset" is nowhere close to a "rebuild".
Second, consider this. What happens if the hour meter goes bad? It gets replaced of course. There used to be a requirement to post in the equipment log book, a notice when the hour meter was changed. It simply doesn't happen anymore. So you need to take the hour meter reading with a grain of salt. So please keep it in mind.
Thirdly, the hour meter IS a required replacement during Tier 2 work. BUT, and I have seen it happen, if the hour meter is not available to the organization doing Tier 2, then the set CAN be issued without the new hour meter.
There are gen sets with 9,000 hours that I would trust with my life. Good engines!! And if the gen set was taken care of during its life, well a quality engine is just getting warmed up at 9,000 hours. We used Stuart and Stevens gen sets in the early 70's that had 10,000-18,000 on the clock, that were simply out best units!
If you can't lay your hands on it, then best to go over the pictures with a magnifying glass. Hope for the best, prepare for the worst!