Check your owners manual, what ever you are over on the GCVRW = the abuse if any. Get your transmission serviced, oil changed and grease anything you can. Check u-joints. Pull in tow haul mode if you have it, I'm sure the 6 speed has it.. Make sure your level. If you have time I would install a transmission oil cooler. Tow at 60 to 65 like the rest of us do and you will probably find that you are ok. But if I were to direct your attention to one thing......make sure that you have not changed the load capacity of that truck by putting different tires on it. Bigger badder cooler tires do not mean the right tires or better tires. Check the actual sidewall on the tire for single tire load rating and inflation. If that does not comport with what you are towing then make it right, or you will lose a tire, before you get going. HEAT kills batteries, tires, and transmissions. Chevy does not make a cheesy transmission and never has. Good luck.