swing arm 92 21 84 18

Bevel drive
outer needle bearing
This one tends to fail because it is exposed to elements.
OEM Inner race part number 92 25 90 25
OEM bearing part number 92 25 22 25 Torrington HK 2516 2RS

Steering Head Bearing
92 24 92 25
30205-J2 SUB305
BB S/Head, taper roller 25x52x16.25

Rear Wheel
The OEM bearing is 6204 2RS1 / C3 90 20 42 20
the bearing is 6204 sealed bearing with dimensions of 20x47x14
NAPA part number is 6204-2RSJ
SKF 6204 RSH/C3 would be best.
Many bikes shipped with too short of a bearing spacer, resulting in premature bearing failure.

front
as accurately as we have discerned, the combination of a 6304 and 6205 appears on bikes with a solid axle.
Bikes with a hollow axle have a pair of 6205 bearings.
6304 is 20 x 52 x 15 mm 92 20 52 27 which may cross ref 92 20 14 20 from older Guzzi.
6205 is 25 x 52 x 15 mm 92 20 18 21