I checked the parts catalog and according to it the Warner T-18 uses the same gear as the NP 435 (C3OZ-17285-C).
One possibility, do you have easy access to the gear? If you do, check and see if there are any numbers on it. If there are I may be able to cross them over to a Ford part number.

 

The YELLOW one is the gear that I keep getting sent by every aftermarket place on the planet...even Ford...the TAN??? gear, I don't know what color that is supposed to be, but that is the one that came off of my transmission...much larger inner diameter and wider gear - does anyone recognize what that came off of?

 

Okay, now I think we're getting somewhere. The yellow gear in the picture, the one that is wrong is a "Type 1". The tan gear that came off your transmission is a "Type 12".
Ford only shows 1 type 12 gear in the parts catalog for the NP435, P/N D3TZ-17285-A. Going through the parts catalog, that was used on an NP435, 3.73 ratio, 9.50 X 16.5 tires...in 1974.
Here's a link to an Ebay seller that has them:
https://www.ebay.com/i/164154113101?...caAkIBEALw_wcB

 

That is AWESOME! ..and kinda funny at the same time...that is the exact Ebay listing that I already ordered this morning when I was looking around, again...hoping that it was going to be the correct gear, again...I have NO IDEA how you figured that out but WOW, that's incredible and very encouraging that it is going to actually fit when I get it in this time!! Thank you soooooo much!! ...you never know the complete history of these trucks when you get them...what has been swapped with what over the years. It seems like a fairly original truck but who knew? Again...Thank you so much!!

 

Once I saw the picture it was fairly easy. The Ford master parts catalog has a page showing the different style gears, both drive and driven and the type designation. After that I sifted through the different listings looking for one that matched your drivetrain. I got to '74 and there it was.
Just glad I was finally able to help you. Stuff like that frustrates me because I know there's an answer somewhere, just got to find it.
As for being fairly original, the newest of these trucks is now 41 years old. The all original, never molested trucks are getting rarer and rarer. And as we all pretty much know, sometimes the worst thing that can happen to one of our trucks is a "previous owner".
Glad I could help.