These will fit the old Triang class 31 (A1A-A1A) and 37 locos. the traction magnets in those are a different design.
3D printed Replacement Axle And Gear For Bachmann OO Split Chassis - square axle
3D printed Replacement Axle & Gear For Bachmann OO Split Chassis
3D printed replacement final drive gears for Mainline / Replica Peak
3D printed Replacement Axle And Gear For Bachmann HO 4-8-4
