I don't understand the ratio chart on page 50 in the Model T Times.
Here's a good chart showing rpms at various speeds with the KC Warford:
Don't know if it's the same?
The KC Warford in OD with a standard 3.64:1 rear gives about the same ratio as 3:1 gears in the rear axle. An old Warford is even taller geared in OD.
There are 3 variants of the KC Warford: "standard" (now discontinued), "H1" and "TT" (just been released).
The RPM chart Roger points out is for the "standard" I believe.
KC Warfords are still available with the "Standard" low gear ratio if you ask for it. Some folks in our T club live atop a hill with a long (2-1/2 mi.) and very steep road with many switchbacks. They have the Standard ratio KC's in their cars and can drive home in Ford high gear with the lower-geared KC's and 4:1 rear gears.
Even though the H1 gearing has been the new standard for several years in the KC's, they still have the old gear ratios in their magazine ads.
The H1 gearing in the first two gears is virtually identical with Ruckstell gearing, while the older "Standard" gearing has a lower speed gear for the low gear, the same as the old Warfords had. The KC manufacturers changed the low gear ratio after getting many complaints about the lower-speed first gear. The Ruckstell (and H1) ratio is just right for most of us.
And they also can make them with custom gearing. Need one with two overdrives or two underdrives? No problemo, but costs extra of course.