[Charlie Down]

Looking at the reference photos most of the arm components of the 1533X2 are at least similar, if not identical to the CMP versions. The arm itself looks like the short arm, with the upper bracket and the hand wheel clamps looking the same as the CMP equivalents.
The arm length scales out at roughly 192mm/7-1/2" which corresponds closely with your measurements above.
I am mid way through drawing the windscreen, but could do with some help with the following:

Wiper arms
Dimensions of the hand wheel clamps, and photos of both sides.
Photos of the hand wheel bracket on the side of the windscreen, plus dimensions.
Wiper motor photos and dimensions.

In the last photo of an operational truck you can see the motor has been removed, leaving a spaced mounting bracket. Does anyone have any information about this bracket? In post 3 there's a similar bracket visible on a photo, but the 1533X2 bracket looks like it has a lip on the lower edge.
Also of interest is the factory photo of the truck which has a different lower windscreen bracket compared to the much more robust looking brackets of 'later' operational truck. This is the only photo I have seen of this 'early' bracket. This may just be photo distortion, but it does look narrower than the other bracket.