In looking at the TC-37F parts manual, there were three different governor shafts listed (251456R93, 355303R91 and 357440R91). Each number has a corresponding serial number range and I would assume that each new number is a design change that would supersede the previous/existing number.
501 to 106701, design one, until April of 1950
106702 to 164222, design two, April 1950 until January 1953
164223 to end of production, design three, January 1953 until the end
I have one of the first number governor shaft (251456R93) and one of the last (357440R91), does anyone have an example of the second number/style (355303R91) that they could post a picture of? The changes from the first design to the last are pretty clear, I would just like to know what the "intermediate" design looked like and what changes were made. I am trying to see what the changes were from one governor shaft to the next, but I do not have an example of the second style.