Mainshaft selector fork

The 57-0260B is a mainshaft selector fork out of the gearbox, the piece that rides in the groove of the sliding gear on the mainshaft and shifts it fore-and-aft when you work the pedal. It lives inside the gearbox shell alongside the other selector fork and the camplate, and it shows up in the parts books under both the inner cover and selectors figure and the selector mechanism figure, so it's a component of the shifting assembly rather than something that stands alone. You may also see it listed under its older T260B designation, which is just the earlier letter-prefix style of writing the same number. Our records show this fork appearing across catalog entries from 1960 through 1969. The factory later revised this part and it was superseded by 57-4308, so if you're chasing an exact fit and your gearbox is later than what's showing in your parts book, the 57-4308 number is worth checking too. Selector forks take a beating over the years from repeated shifting, so it's worth pulling the gearbox inner cover and eyeballing the fork fingers for wear or a sloppy fit in the gear groove before you put a box back together around a tired one.