Easy to print Scammell Pioneer R100 (artillery tow), 1/100 scale, will want some greebling if scaled up. Some details have been changed for looks/ printability.
Look at the images for assembly details. There are small marks on the frame where the leaf spring ends line up. Leave the rear wheels attached in their pairs for easier assembly onto the suspension.
Scale by 1.56 for gaslands / hotwheels / 1/64
Scale by 1.786 for 28mm / 1/56