Does your generator have a spring steel band around the housing on the opposite end from the pulley, or is the housing solid? If it's got the band, remove it and look for the terminal post that is connected to one of the brushes with a flexible pigtail wire. That one is the Armature lead. The same information can be learned by removing the rear plate of the solid-housing generator, but be careful that the pieces don't fall apart- - -the through-bolts hold both ends on.
Jerry