Speedometer Gear Question

[Robert Crandall]

I am working on a Saginaw 3-speed with overdrive that I will install into my truck when I get it ready. I do not know the year of mine, but I believe that these were made between 1966 and 1970. I do not know what differential ratio it was set up for, but it has a 24 tooth driven gear, natural colored. The charts that I have found do not show 24 teeth as a choice. I have been scouring forums, but I cannot find anything that I can understand or follow.

Can anyone direct me to information that will show me what driven gear I need to use this transmission with a 3.73 differential? Thanks!