One of my projects these last couple of weeks has been this trio of poorly taken care of Flyer #21165 locos from a junk bin. I fully rebuilt all three and they run beautifully. The badly rusted one on the top was a challenge but overall I think it turned out okay.
It’s actually quite simple, I just gave the corroded side rods a few hours in distilled vinegar, then washed and wiped them off in water. Did a beautiful job on the corrosion and the rust.
Nice looking locomotive! It’s a bummer these tend to get overlooked because they really are decent locos, they just don’t have much to offer in the looks department. With that in mind I find it interesting that the 21168 is harder to find despite being a spruced-up version. Maybe in those days it was on the expensive side for practically the same product. An interesting project could be adding the real connecting and side rods from a 21168 to a 21165, to replace the fake ones. In my opinion just that would make it look way better.
In my service manual the chassis assemblies are also separate part numbers, XA30N061 for the 21165 and XA30N061-A for the 21168. I would guess there are mounting differences for the motors to account for the smoke unit.