OEM Part
Name: Bevel Box Needle Roller Bearing (RH side)
Moto Guzzi Part Number: 92252225 Needle Bearing/Outer Race, & 92259025 Inner Race.
Replacement Part
Brand or Source: Any Bearing Retailer, but in NZ: SAECO Wilson were great.
Part number: HK2516.2RS Needle Bearing, LRTZ202518 Inner Race 20x25x18.
Differences from OEM: No hole in inner race. This is a good thing.
Comments: You can't knock the old outer race out from the other side of the bevel box. If heat, rapid freeze, and slide hammer don't get it, then thin-walling with a dremel is your only option.
When installing the outer race, the end with writing should face outwards, as it is usually designed to withstand installation press loads better than the unmarked end.
After installation, packing it with waterproof wheel bearing grease before fitting the axle should help it last, as rust seems to be the main reason for failure.