I've just replaced the engine on my 18.5 hp Craftsman lawn tractor. It
has a Briggs engine (31P7770296E1, 18.5 hp OHV Intek Plus). Although I
replaced the engine with the exact same model number there is one wire
configured differently on the new engine.

The old engine had one wire attached from the flywheel to the
regulator. The new engine has two wires connected to the flywheel.
I'm assuming one is a hot wire to the regulator the same as the
original engine and that the other wire is a ground.

Can anyone provide any information on this or direct me to a schematic?

Thanks,

Darrell