These are the main speedo gears in the saginal and muncie manual GM gearbox range.

Different teeth will result in different speedo readings.. as does the effect of tyre height and or wheel size changes.

Somewhere on google you may find a speed/tyre/ size formula to help.. but in the meantime..

Here is the main 5.. with teeth  18 - 19 - 20 - 21 - 22

They are for use with the 46mm driven gear. They are 44mm long with a head OD of 19.8mm.

Choose what is needed.

ALL COME with a new seal as well.