Hi Lou, Does your information happen to indicate when Dura-Ace had used (and then discarded) their "Center-Pull" brakeset?
I have a 1974 catalog which shows the Shimano center-pulls as "Tourney" components: [model B-110 = 47-65mm... Model B-120 = 57-75mm]. However, I also have an actual pair of Dura-Ace calipers, which were identical, and those did not appear with the '74 listings.
Thanks!
Bob Hanson, Albuquerque, New Mexico, USA