I have a 2014 GMC sierra 1500 C-cab short box 4x4 with the 5.3l and 3.42 diff gears. I have a 24 ft holiday trailer loaded about 5500 lbs and even on flat highway it is not surpassing 4th gear. I pulled my sisters trailer when their truck broke down and loaded it is 7700 lbs which is well within the rating of the engine and gear ratio yet it won’t shift passed third. I am very disappointed because I traded my 2005 2500hd duramax and I never expected the 2914 to not be able to use all 6 speeds towing either of these trailers. I live in Alberta so I would like to head into the Rocky Mountains but wondering if I will be able to keep my trailer which is just over half the rated tow capacity for my specific truck at a decent speed since it won’t surpass 4th gear on flat highway. Does anyone else have experience in this? I have recently added an diablosport tune, aftermarket air intake and a cat-back exhaust all claiming hp and torque gains. Unloaded I have noticed a huge acceleration increase but I have not had the chance to tow until spring comes now. So I’m looking for advice if anyone has this experience or if I made a mistake and should look into a truck with the 6.2l before camping season arrives?
