The output shaft that comes out of the gearbox and connects to the idler gear is PN: 118497 (smaller gear). The idler gear which connects the output shaft to the main drive unit sprocket is PN: 093061 (medium gear). Those part numbers do not include any of the snap rings, bearings, square keys, or flatwashers. Those parts can be resued after removal if they don't get broken or bent.
All the other gears are sealed inside of the gearbox. Let me know if you need part numbers for them too.