Per Jinks' book, the Model 29-2 started at serial number S227149 when the switch to the 3-screw frame was made. The lowest serial number for a 29-2 I have actually seen is S227832. In 1962 and early 1963, there were revolvers stamped MOD. 29-1 in the yoke cut (and a few stamped MOD. 29-2) that have a 3-screw frame and an extractor rod with the old style, right-hand thread, as S&W as using up its old parts. By early 1963, at around S230000, S&W was shipping revolvers stamped MOD.29-2 in the yoke cut and correctly configured with a 3-screw frame and an extractor rod with a left-hand thread.
1962 and early 1963 was truly a period of of transition for the Model 29. The Model 29-2 was produced for approximately 20 years until the Model 29-3 was introduced in 1982 at a serial number in the high N800000 range.
Revolvers in the S270000 range were shipped in 1966, long after the Model 29-2 was introduced.
Bill