@chametl,
First, Welcome to the Hobby-Machinist!
It's great to see you jumping into discussions.
I think Glenn might be right.
Do the threads you cut match a metric thread pitch?
Have you found a manual for your machine, or a similar one?
You'll probably find that the quick-change gear box(QCGB) ratios are common across multiple machines.
This means that the change gears on the headstock will also be common.
We have a section for Cincinnati manuals here:
https://www.hobby-machinist.com/resources/categories/cincinnati-except-grinders.30/
In particular, check this manuals to see if you can find the original gear ratios:
https://www.hobby-machinist.com/resources/cincinnati-traytop-lathes-manual-pdf.2039/
Does the plate on your lathe list the same thread cutting range as in those manuals?
If you post the teeth counts of every gear from your spindle to the QCGB input shaft, we might be able to help more.
Especially for the two gears that might not be original.
The tooth count is usually marked in the numbers on the side of the gears.
-brino