I have a similar engine. Its data plate gives model number, serial number and cu inch. Mine is a 4 cylinder, 32 cu. inch, aluminum engine used in a military generator. I bought it because I thought it would make a good ultralight plane engine. weighs about 55lb. I think they have 4 cylinder around 56 cu. inch again generator engine. I kind of looks a hair different than mine. so maybe it is the 56 inch-ish engine.