Mine — bought used a few years ago — has the s/n 518762. I have been told that this means a 1960s build/shipping date. Does anyone have a lettered shipping date or sales receipt for another revolver that could narrow the range a bit?

Based on the list I maintain I'd say you're in the spring of '67.

__________________
Wrangler of stray Chiefs
Bob

Early J frame serial numbers
For models 36, 37, 38, 49, 50 and pre model number versions.

1950 = start at 1
1952 = 7369 - 21342
1953 = 28916
1955 = 55050 - 75000
1957 = 117770 - 125000
1962 = starts at 295000
1969 = ends at 786544

J serial Prefix serial numbers.
For models 36, 37, 38, 49, 50.

1969-1970 = J1 - J99999
1971-1972 = 1J1 - 999J99
1973-1974 = J100000 - J250000
1975-1976 = J250001 - J370000
1976-1977 = J370001 - J610000
1977-1978 = J610001 - J670000
1979-1980 = J670001 - J760000
1981 = J760001 - J915400
1982 = J915401 - 1J18600
1983 = 1J18601 - 1JXXXX

1955 - 4 screw side plate ends
1957 - stamping of model number at 125000
1966 - flat latch ends
1968 - diamond grips end
1975 - heavy barrel standard
1982 - end pinned barrel