black boards and black metal strips, until 1955-2nd series trucks?
except for, maybe, the deluxe 2-tone exterior/interior paint options in 54/55-2nd

http://www.oldchevytrucks.com/blog/index.php/2010/02/truck-beds-black-wood/

Some people claim the "black paint" was coal/lamp oil (creosote) with lamp black ("Lamp Black or lampblack is a soft bluish-black pigment that is very stable and unaffected by light, acids and alkalies").