Some of the transmissions have shallow grooves ground into the spline on the input shaft where the clutch fits. Depending on the number of grooves, it identifies the gear ratio progression for the transmission.
Jerry

"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln
Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt!
There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. - Ernest Hemingway
Love your enemies and drive 'em nuts!