They have a Grip washer that slides over the axle, same flats.. , Its part of the torque transfer to the frame.

You can add a spacer on the axle under the lock nut to match the frame ..

Pay attention to the chainline on the right, then when all that's right ,
center the wheel [dish stick, gage] between your axle lock nut ends.

3 speed cogs are made from 13 to 22 teeth to get the gear range
where it will work best for you

Sheldon's suggestion was High gear in the mid 70" range

with the external ratio giving about a 57" gear
I have a 77 for the high..

Steel frame can be cold set to change rear dropout spacing ..