It is at the inflection point between 2 and 3 digit endlinks. I think that it is possible that it originally came on some Speedmasters (145.022), but any 20mm lugged watch from between 2nd quarter of 71 and some time in the early 80s, could have potentially be used on a 47 endlink, as they were supplied at the boutique when someone was purchasing a watch.
The 47 end link number is absent from Mstegnas chart, linked above. I would bow to his authority on this one, but I would very much like to see if anyone has a seen a 145.022 that originally came on 47 endlinks.
