every 1013 such as these...
It was three years between seeing my first one and my second....another year and a half until I saw my third.
In total, in eight years, I've seen exactly 8 (4 in the flesh) and I am happy to have 3 of them.
36mm non date w/ 20mm lugs...only in 18k. 1570 movement. Though they are listed as being produced in the 60s, 70s, and 80s...none of the 8 I have seen were made after 1967 and two were possibly made in 1959. Probably was more of a dealers special order option for customers who wanted the 18k 36mm case, but with out a day or date. ( The more common non-date OPs were 34mm w/ 19mm lugs.)