Hi,
Documentation on the AX series is sparce at best,
Originaly the 600ax has three models 6300 6310 and 6322, thats plain round, round to oval and all oval respectivly.
Despite its short life its obvious and even the documentation backs this up, as well as date codes stamped on most if not all shimano components, the parts and bikes koga and other had a four year life?
The date codes confirm this.
Some experts back up a toe clip made of alluminium alloy for the ax series!
I have two if not three different 600ax brakes clearly not the same at all!
And I dont mean front and rear either.
There are also some subtle differences in the dura ace brakes to, and also late 600 ax calipers which are same mold as dura ace ax!
So the seat pin you have I'd guess has a late date code?
Might be diffecult to find if it exists at all.
Depends how near concours you are going?
The "shimano 600ax" stamping on side of pin would denote that its an all oval pin 6322 but I am guessing that they mixed it up a bit on the last runs?
Regards,
