145.022-68, one of the first made, #26556247, 1511 serial numbers later.
(Last time I checked with ilovemyspeedmaster, the 861 comes back as March 1969 but the 321, with an earlier serial number, comes back in April.)
I have put a better bezel on it since this photo.
And, I’ll throw in this 145.005-67, roughly February 1968.