I haven't been able to locate any serial numbers on the frame. If anyone can tell me exactly where to look I might be able to scrape off enough paint and crud to find it. I have come to the conclusion that the engine is not the original. I can't find anything anywhere that mentions a model with a 2 cylinder Wisconsin engine. The 600s had a Wisconsin, but by everything I have found so far, they are all 4 Cylinder. I even called local dealer and talked with the parts guy, and he said its likely not original. With all that stated I am going to assume that mine is a Melroe 444 (M444) and go from there till something comes up that proves me wrong. Since the engine isn't original, its likely that anything not directly engine related is interchangeable anyway, so I should be ok. Now I just gotta get her to quit leaking all over the place and I might be able to use her! Anyone done the rear axle seals on an M444?