Need help on chevy avalanche/ cadillac ext conversion?

[romantic_pleasure]

Im planning on purchasing a chevy avalanche but that plastic piece that runs along the bed of the truck looks too fake. How do I go about replacing that back piece to match the one that comes stock on a cadillac ext? And what's the proper name of that part?

 

[biddies]

them american cars, why not get a german or japanese
an avalanche is a avalanche you dont want to go spend that amount to just make it like a caddy