The original model was a Brekina WWII US Army canvas-topped stake truck. It was army green of course, but the main reason I bought it was that the canvas top was removable. It had a Mercedes Benz logo as a hood ornament and that was the second thing to go. I just snipped it off leaving a little bump which I would deal with later. In my case I wanted the truck to be a more prototypical dark blue, so the first step was to remove the wheels (easy on this model), mask the windows with liquid frisket and airbrush the whole thing with thinned Polyscale. To paint the wheels their first coat of blue, I just use a brush. It's easier than masking the tires and looks fine. I also use a brush to add rust and mud. Once dry I airbrush the undercarriage with Polyscale Mud, or whatever you've established as your dry earth colour. This is the single most important step in getting the dusty well-travelled look. Turn the vehicle upside down and spray from below. Turn it a couple times so you get every angle. You don't need to be an airbrush wiz for this to work, just keep your spray light. What happens is that overspray gets onto the sides of the vehicle in exactly the same physical way that it would in real life. If you do nothing else to the model this produces a great effect.