I just bought a MEP-002a from GL that was a runner (mostly) with 2060 hours showing on the hour meter, the generator end is dated 1976 and has obviously been through the rebuild process at least once. Stenciled on the side was a "serviced" date in 2008. (voltage would spike on it, fixed by replacing a $5 transistor, battery meter was full of water, and there is still something wrong with the votl and amp meter where it goes flaky from time to time, but it runs smooth does not smoke and generates power). In the same GL event there was one MEP-002a showing over 8,000 hours on the meter, take that for what ever you think it may mean. I do know of people getting close to 20,000 hours out of Onan DJB's which is the civilian version of the same engine.
Ike
p.s. I should probably mention my MEP-002a is an ugly duckling, data plate, front panel and top plate so faded as to be mostly unreadable, it has a nice sprayed on somewhat faded coat of green camo CARC, that someone brushed over with some splotches of tan, etc. but from a mechanical point of view it is well maintained and runs good.