I used rustoleum red oxide primer, salt, and Krylon pistachio, after it dried, I scrubbed the salt with water and a toothbrush, and then used a cosmetic sponge and a light light light amount of acrylics to add the grime...
Been a while, but I wanted to work on this again after seeing Chuck Most's C series trucks...
I finally have a rolling chassis, and the front bumper has been painted, gonna grime it a little bit...