I was wondering something. There are a couple of engines on e-bay for sale now and I was wondering if someone could elighten me on something? The engines on e-bay have what looks like alum. flywheels and steel shroud along with a name plate on the back side of the crankcase. I have one, but the shroud is brass, the flywheel is brass, and there is no place for a name plate on the engine anywhere. What is the logic for the differences? Is mine older? And if so, how can I tell the age of it? Any help would be appreciated. Thanks!!