Ok.
What we now know as the Model 10 started in 1957 as a continuation of the Military & Police Hand Ejector .38 Spl.
Supica & Nahaus actually start the Model 10's chronology in 1945 with the beginning of the "S" serial numbered guns.
But, for the numbered guns:
10 -- 1957
10-1 -- 1959, introduction of the 4" medium-weight (mwb) barreled gun.
10-2 -- 1961, Extractor rod change, r to l hand thread on light weight (lwb) barreled gun.
10-3 -- 1961, same as 10-2, only on mwb, sight changed from 1/10" to 1/8" inch.
10-4 -- 1962, trigger guard screw eliminated on lwb.
10-5 -- 1962, Sight changed to 1/8" on lwb.
10-6 -- 1962, trigger guard screw eliminated on mwb.
10-7 -- 1977, gas ring change, lwb.
10-8 -- 1977, gas ring change, mwb.
10-9 -- 1988, New yoke retention system , lwb.
10-10 -- 1988, Same as above, mwb.
That's as far as my book goes, 1994.