What's the part # for the OEM Dually bed caps for a 2005?

X2

X3
I'd like a little info on the same part , but for an 07.5, new body style. Do they offer the bed rails in a diamond plate, or just the plain old black plastic?

Check w/ GM Parts Direct, they list them for a regular 8 ft bed, might call them they sell the dually bed and other bed parts.

2001-2007 It appears the PNs are 15932236 right and 15932237 left and they are listed as molding - pickup box side upper

Once you get the part numbers I would shop around for price but im not a fan of ebay for auto parts. I usually order parts from Chevy parts (http://www.gmpartsclub.com) since ive had good luckk with them.