A series of questions spring to mind.
1.? Do you have a weight distributing hitch with an anti-sway system on it and has it been properly adjusted?
2.? Is that trailer weight a manufacturer's specification for a dry weight, a gross vehicle weight, or is it an actually scaled weight of the trailer loaded for travel?? ?(The first is a mfr's guess, the second a good estimate, the third is reality.)
3.? ?Do you know of the Trailer Life Towing tables?? ?They can be found online at
www.trailerlife.com.? ? Go to the Tech section.
Assume for a moment that your given trailer weight is a GVWR or a scaled weight.? ?We recommend that you allow a tow rating safety facture of 10% compared to trailer weight or GVWR.? ?For a 6600 lb trailer the truck should have a tow rating of at least 6600/0.90 =
7,333 lbs.? ?For towing in the mountain or Pacfic west, make that safety factor 20% so the tow rating should be at least 6600/0.80 =
8250 lbs.? ?Now go to the Trailer Life Tables and look for trucks using these numbers --? but be sure to derive them your self from the real weight or GVWR.
In your search, do not confine yourself to GMC products. Ford and Dodge make fine vehicles in the 3/4 and 1 ton ranges. I realize that folks tend to evangelize for certain marques with almost religious fervor. Relax, the things are just machines and every mfr has made jewels and junk. If you have to haul a lot of passengers, rather than going for SUVs, consider the E350 vans of Ford. Those big rascals can pull a whole bunches. ;D