Try a napa store for a gear listing. Probably the best bet for a new one would be a dealer. What I've done before is take the gear off the original starter and put it on backwards after radiusing the end of the teeth with a deburring wheel. In a pinch this works very well, I ran one for 50k and it was still working well. swapping the gear is pretty easy, just remember to only use a dry lubricant if anything on the shaft. They like to be clean!