try lmc truck...
i get their catalog and they have one in there.
their basic one is 49.95..part number "49-3708"... this one turns on with your tail lights, brightens with your brake lights, and flashes with your turn signals... mounts in between your tailgate and bumper. however this is only red LEDS
their upgrade one 59.95.. part number "49-3706"... red amber and white LEDS, running lights, brake lights, turn signals, reverse lights
if i hadn't just spent 300 bucks on repairs from an accident (because the lady was supposed to give me the money for it ((we WERE handling this outside of insurance)) while it was in the shop, but then she decided to ignore my phone calls and what not.. so i turned it into her insurance, but in the mean time i needed to be able to drive so i had to pick it up and pay for it out of my pocket), i really like the upgrade 3rd light.. really fancy. not too expensive either...
they are both 49" wide and they stick on with self stick tape. they wire into the factory hitch plug, or if your truck is like mine and doesn't have that.. you can also hard wire it (which kinda sucks... just not as easy you know? lol)