A good friend of mine sent me a pair of Kenworth T600 tractors made by Showcase Miniatures. These are no longer in production, and hard to come by I believe. They compliment my T800 nicely, and thought they would look good on a bottom dump or grain trailer. I took a few minutes the other day and added DOT striping to one of my Trail King trailers, and also added mudflaps. Overall, this is a fairly easy project, and I have been really impressed with the print quality on these particular models.
Here is the link to Shapeways if you want to buy your own: N Scale Trail King Bottom Dump Trailer
My DOT stripes are very simple. I create a white/red alternating ribbon using regular paper, and then coat the back of it with spray adhesive. I use MS Excel to make the stripe and then print on my inkjet.