Mavic Monthlery rims date, I believe, to about 1959. My 1962 PX-10 had them, past tense I just got the rims which were, alas, both out of round. There was also a cherry condition 1959 Urago on eBay a few years back and I recall this having Monthlery rims. So a real classic in production for about a quarter of a century.
Peter Kohler
Washington DC USA