I am not a gas Cat Guy, but I believe your machine calls for a Gen. with a pulley not a gear right? If so, you might be able to use a Delco-Remy 1102710 35Amp Gen. These and similar ones were found on 1940's GM product cars and trucks. You will need to have a Gen. bracket and strap etc. I put one on my D2/3J although I had the Cat Bracket and Strap already. Just had to make a new strap to fit the slightly larger Delco Gen. It fit real nice in the Bracket. The original Gen. was an American Bosch lights only unit which I still have. Needed to convert Because I added a Cat Electric start pony system to my D2. The voltage regulator to use with the Gen. is a Delco 1118301. Hope this helps you out.
My cat twenty two that had a gen uses a gear not a pulley.
Yes you are right I need a gear driven. Any Idea where I can find one