we can get fairly close on the dates: first appearance was in the 1972 catalog . . . my guess is that they were made into the mid-1970's.

in terms of the number produced, I do not know of any records or reliable estimates of the numbers produced. We try to track how many we see in the current market; current estimate is that we see 20 Samples Per Year ("SPY"), counting all colors, and counting only good quality samples, but not counting numerous fakes and refinished dials.

Jeff