wc,wd speeds

Does anybody know the difference in 1st gear speeds on a WC, WD, WD-45, if they all had the same size tire and running the same RPM's? In looking at the manuals and Nebraska test it appears that they all had a rated speed of 2.5 mph in 1st gear, but ran different size tires. So where the rearends geared different?

The actual internal transmission gears between a WC and old WD are exactly the same parts (just located in a different case) and are 2 1/2...3 3/4...5 MPH. The WC is rated at 1300 rpm and WD at 1400 rpm but the slower ring & pinion and final drive ratios in the WD allow for 100 more RPM and maybe a little bit bigger rear tire and still wind up with almost the same actual ground speed. The late WD and all WD45's had a slower 1st gear of 2 1/3 MPH but second and third gear were still 3 3/4 and 5 mph. As I understand it, the slower low gear was for harvesting of better crops as years went by. The WD45 diesel ran 1625 RPM so the rearend ring and pinion was slowed down to make the ground speeds once again 2 1/3....3 3/4.....5 MPH even with the engine running at 1625 RPM.  A-C always wanted 2nd and 3rd gear to be for plowing and discing and knew what MPH generally worked the best. Another way to look at this would be a WC running at 1400 RPM will be traveling 2.7 MPH instead of 2.5 MPH at 1300 RPM.   (2.5 mph times 1400 rpm divided by 1300 rpm equals 2.7 mph).

He's such a better "explainer" than me lol