Some original documents referring to the Chevrolet 133" wheelbase trucks. The "W.B." in these documents caused some confusion, but these are in fact Chevrolet WA trucks.

(via Brendan O'Carroll and John Valenti)
From the “Desert Chevrolets” article in Wheels & Tracks magazine no.8 I copied the technical details of the 1940 Chevrolet WA.
Edited to add: the above information refers to the Chevrolet WA 30-cwt truck used by the LRDG before the 1533X2 was taken into service