Not only that, there are typically multiple gear ratios available that will, sometimes drastically, change the tow rating as well. The two options available on my Tahoe was about 3800 lbs difference. Unfortunately, most factory orders come with a "highway"gearing for fuel economy and better towing gears usually have to be ordered. The result is that finding a used vehicle with a good towing gear is sometimes difficult. Make sure to verify what it's got in it as a lot of reviews will only list the max tow rating "properly equipped".
2012 Chevy Tahoe LTZ - HD tow package
2017 Rockwood 2703WS Emerald Edition