Gmc 3500 crew cab dually with the 6.6 duramax diesel and allison automatic can to perform its designed job with out over heating. truck is rated for 23,500 gcwr and a 16000 towing capacity. however it struggles to pull 7000 pounds and engine temperature got over 230, and transmission temperature over 210. the cooling fan struggles to control the heat and runs constantly, the noise is unbearable. if one were to attempt to pull my rv up a mountain grade in the summer i would be left stranded on the road or in traffic. *nm