replacing older SD45 axle gear

[Capt. Brigg]

I have an older Bachmann SD4 that the plastic axle gear on the middle axle has split and now clicks when running the engine. The gear does not look like the 00M02 gears shown on the parts sheet for the DCC model SD45 on the website available parts sheet. Mu gear has a wider sleeve that the metal axles slide into. Where can I find a part number for this older axle gear, where can I find the gear, and how to order it? Thanks for any assistance.
Capt. Brigg Franklin
CEO Pacific Cascade Railway in HO scale.
Capt.brigg@pacificcascaderailway.com