Note the Shimano date codes page at the CR site:
http://www.classicrendezvous.com/
Z and J first generation?....Not according to the codes, way later.
Dennis Young Hotaka, Japan (what a mother of a typhoon that just visited here)
>
> I have a set of the satiny high flange Dura Ace track hubs,I believe 1st
> generation.Both hubs have a letter Z and J marking on the barrels below the
> stamped Shimano logo.Any ideas as to what these markings signify?
> Cheers,
> Todd Kielman
> Chicago Il.
> ---------------