If the metal tag is still on the starter, the 6V ones have black paint, and the 12V are red. The 12V has a smaller-diameter armature shaft that the 6V, but I don't have a measurement handy for either one. Both starters have the same number of gear teeth, but the tooth pitch is different, IMHO.
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
Love your enemies and drive 'em nuts!