[G Baese]

The Ruxtell axle is a two speed rear axle. The standard Model T ring gear has 40 teeth with an 11 tooth pinion. This would give a lower low, a standard low, a lower high and a standard high. Great for hilly runs, especially in a heavy sedan.
While the ring gear remained 40 teeth, a 9, 10, 12 and 13 tooth pinon was available, giving both under and overdrive capabilities to the standard ratio.
The nine tooth pinon gave a 4.44 to 1 rear-end ratio; the 10 tooth pinon a 4 to 1, the standard 11 tooth gave a 3.63 to 1, the 12 at 3.33 to 1 and the 13 tooth pinion gave 3 to 1, the most commonly used ratio for roadsters and flat-land touring, which in effect is an overdrive.
Hope this adds a more complete look at how a Ruxtell 2-speed rear-end could be used.
Best regards and Happy New Year,
geary