I believe seakaye is correct in the manufacture
being Duo-Trol. The gear on the mag plate
was probably available for either magneto
or possibly you got both gears as a kit. The
assembly must also fit the block. There seems
to have been one available for the smaller
CI motors as well.
Tubs
A "Boathouse Repair" is one thats done without having tools or the skills to do it properly.