Unfortunately, you're going to need a complete flywheel, not just a ring gear. The inside diameter of the gear, and the machined surface of the flywheel is different for 6V and 12V, as well as the tooth count on the ring gear. Either one has the same bolt spacing for the crankshaft.
Jerry

"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln
Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt!
There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. - Ernest Hemingway
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