It may be the perspective that you took the picture at but the bottom gear appears to have a greater diameter than the top. Hopefully that is not the case or now you would have 3 different axles
The early style axle did not use a bushing - it attaches to the fuselage bracket with a AN5-14 bolt and AN310-5 nut. Perhaps if the hole becomes worn you can drill it oversize and install the bushing. The reason they used bushings on later models was so they could be replaced.
The later style used a bushing (PN AS-5-5-902) and a AN5-15 bolt.
While we're at it - on the early style the bottom bracket on the axle accepts a AN6-22 bolt while the later style MAY be drilled for a AN7-27 (7EC). I have the later style axle on my champ but it was drilled for the smaller bolt. When I installed new no-bounce oleos on my aircraft I had to get an oversize bushing from Safe-air (now wag aero) in order to stay with the smaller bolt.
Since you are obviously going thru the landing gear I would suggest that you check carefully for any slop in the landing gear attachments. With the oleo type of gear this is a concern, but there are fixes if you find any.
Bonne chance!
Tim