Anyone clued up on older HD pinion shafts??

ive got a set of flywheels here & l need to know what the pinion shaft suits?

l cant remember if its about 1958,,1974.or other..

since HDchanged them a few times over the years.....

Its still attatched to the flywheel,

So i've measured the shaft ,from the groove closest to the flywheel to the very end of the shaft,

it measures 121mm.

Anybody know the year of this baby????