I had one put in a few weeks ago (RCLB 5.7) for the same reasons larry wants one. $100 installed. I have not heard of them coming standard in the states on other sites, so it may be a dealer choice to have one set up that way before the truck sold. My chord is zip tied to the radiator mount on driver's side, and pulled it through the grill. It's a 300w heater and plugs in to the engine by the firewall. There is a heat shield wrap around its wire/chord for about 3 feet down to the block, but not the entire length.
FYI, it takes about an hour to heat up 12 degrees at about 30deg F., maxing out at 3 hours.
Your dealer's parts department needs to call another dealer to find the appropriete part number aparently.