The spotting differences for the H8, H9 and H10 classes are:
H8: integral cast cylinders and saddle with inside steam delivery; no sloping external steam delivery pipes to the cylinders (like the first photo above).
H9: external steam delivery pipes to the cylinders with snifter valves (the round part at the top of the cylinder where the sloping pipe comes into it, like the second photo above).
H10: external steam delivery pipes to the cylinders without snifter valves, like the photo below.
Mark in Oregon, that is indeed the generator between the stack and headlight. The first photo shows an oil burning headlight, the second photo could be an electric headlight in the old oil burning housing and the H10 photo above shows a more modern electric headlight.
