The Soviet Voroshilovets was, like its immediate predecessor the Komintern heavy tractor, based on the chassis of the unsuccessful T-24 medium tank. They were widely used throughout WWII, and in the latter part of the war were supplemented by a very similar vehicle based on the T-34 chassis.
I designed this model in Blender quite a while ago, and
put it up on Shapeways, but since then I've redesigned it for home FDM printing as well. Unfortunately, my online shop of choice, Wargaming3d.com is down for maintenance at the moment, so the STLs won't be available until it comes back on line.
The tilt is detachable too, in the event that you prefer your artillery tractors in the nude.