The 37mm Bofors anti tank gun featured in the earlier phases of the 1940-43 Desert War as one of the original portee anti tank equipments of the Western Desert Force, and what was to become the 8th Army.
There is a good picture and write up of the weapon at http://www.btinternet.com/~ian.a.paterson/equipartillery.htm, and other web-based sources, including pictures, are easy to come by.
What is clear is that the 37mm Bofors ATG is not the same or similar to the more famous Bofors 40mm AA gun. So I would avoid putting a 40mm AAG taken from the forthcoming Zvezda release, or the existing Airfix model, on the back of your Chevys and calling it a Bofors portee.
How about scratckhbuilding the 37mm from plastic rod and pastic card. It's a small gun, and a bit of patience would probably give you some good results.