18 tooth "S" 1275Gt Ist motion shaft for later A plus layshsft/mainshaft use. Used by competitors who have to use standard gears but wish to upgrade the 14mm end of the mainshaft to the later 18mm type with the larger bearing to give better longevity. Fitted 1979-81 as standard on 1275GT and will work with laygears stamped
DAM3168 and
22G1040.