I ordered them from someone. They are peel and stick. And kind of thick. I can't remember who I got them from. But you could make your own. Print it the size you want on plane copy paper, cover with clear packing tape. soak in water, and when it's completely wet, you can start to rub the paper side off...and you have a "decal" the tape should be sticky enough to apply to your box truck. Or you could just print the logo on decal paper.
