Hello. First time user on this site. I purchased a 2013 GMC Sierra 2500HD 4x4 with the 6.0 vortec, nine months ago. I have the 3.73 gears and the truck has 73,000 miles on it. I have not found anyone else who has this issue: While pulling my 27' TT(5,000 lbs empty), the right side CAT became extremely hot. The floor became so hot, my wife could not leave her feet on the floor. It was pouring rain & we had been on the road for about 4 hrs. The carpeting in the front passenger area was also wet. Other than that, the truck seemed to be running normal. No check engine light, coolant & tranny temps were normal also. Had two different mechanics check the truck over, with no detected issues. No codes were detected either. Using a heat gun, I've noticed the passenger side floor runs 75-100 degrees hotter than the drivers side. The heat shield is in place. Has anyone heard of this issue? GM says they have no bulletins related to this. Sorry for the long post, but I'm trying to include as much helpful info as I can. Thanks!