the heater element is located in a freeze plug on the drivers side of the block closest to the firewall. I would look for it there. Then follow the cord until you find the end. I have heard that some do not come with the cord and others you have to pull apart the driverside fender well to get to the cord.
Thanks all, even though the salesman at York Chev in Brazil, IN said my truck didn't have one the service department at Rod Hatfield Chev in Lexington, KY sure found it and uncoiled it for me. When I got home I had plenty of cord to run it through and out the front bumper below the radiator in the slot in the bumper. Had another 10" of cord hanging out when I pull it out. Its a good spot as even at interstate speeds the cord sits in that spot just fine when not in use.
Just as Pikey said above the cord ran off the block heater plug on the passenger side. If I could have seen in there it would have been easy to do myself. It was pretty much in the same spot as where my Cummins trucks were.
I have a 2012 3500 hd denali with 6.6 duramax I found plug tie wrapped on passenger side just below the red cable leads. Cord is black so it won't jump out at you ,have a bright light.