I have seen several of these exact style through the years, and all were white. However, it could come in any color really. The key thing with these is that many trucks back then were sold without back bumpers which allowed dealerships to either offer them in multiple styles in the show room, and buy cheaper/more styles from a third party to sell. The chrome ones were usually factory made (if they look almost like the front). There were some after market chrome ones too but they tended to be heavier built for hitches. Most bumpers that were painted came from after market sources. The dealer sold you a truck, and said- ya want a bumper to go with that? Since you already have a white top, it would probably look good to match that color anyway. Hope this helps!

if it is a diamond plate step bumper it was most likely black.try finding a groove or joint and scrape it color might still be in there.