What was the time period during which that style of ejector rod end and front sight were found on the same revolver?
The short answer to your question is from 1933 to 1950 on fixed sight guns all frame sizes. But lots of clarification is needed to know the entire answer and the reasons.
BACKGROUND:
The straight extractor rod with knurled tip (no knob) was first used on pre WWII 2" barreled hand ejectors; the I frame in 1936 when the first 2" 38 S&W Terrier was introduced; the K frame in 1933 with the 1st 2" snubbies; and not on the N frame until after the war.
It was designed so that it would go all the way into the yoke flush for maximum reach to extract cases.
During that period all other barrel length hand ejectors used the barrel knob first introduced in 1927 to replace the mushroom knob. The exception was the N frames with an extraction rod shroud under the barrel which was first introduced on the 44 Triple Lock in 1908.
Pre war extractor knob change 1/22/27 to 'barrel' style with barrel notch shown:
The straight rod was less costly to produce especially because it no longer needed the underside of the barrel notch milled for the barrel knob.
But after WWII, S&W would not scrap notched barrels in inventory just to change over to the straight post war knob-less rod. As we know S&W didn't scrap anything they didn't have to, so they attempted to use up the notched barrels in inventory by using barrel style knobs. Also as we well know, parts were not used in any particular order when assembling guns. So it's easy to understand post war assembly of un-notched barrels w/straight knobs being assembled first and/or mixed with notched barrels and barrel style knobs.
So all frame sizes in the very early post war years until ~1950 will be seen with barrel knobs/notched barrels as well as with straight rods with knurled tips.
NOTE: recognize the extractor rod thread on I frames only were changed from right to left hand thread soon after the war; much earlier than K and N frames (~ 1960). Therefore on early post war I frames, barrel knobs will be found in both right and left hand thread.