Hey Matt- I'm thinkin' that the MIL rating for power out of that genset was around 8-10kw. I don't think that model ever had a non-mil derivative, but in real life, you'd probably be able to get 20hp out of that Onan. Quite a few of the Onan liquid-cooled gensets were intended for marine applications. Most were gas, and fit in the MCCK designation, but that was Onan's classic opposed-cylinder arrangement, with water-jackets around cylinders, rather'n air-cooled. You'll probably find that it's governed TIGHTLY at 1200rpm. If you can find the fuel cutoff linkage, and flip it in the other direction, put some diesel in the supply pump's inlet, and roll it over... it'll probably puff, pop, and go. Watch 'yer fingers!