Lost your owner's manual for the 2006 GMC Sierra 1500 and do not know what your towing capacity is for hitch safety purposes? Do not worry. We have you covered. We went out and found the owner's manual for you here. Please note that this is a Dropbox link and you can download the manual if you so desire. We can even tell you that the page you want is 4-67 if you are looking for towing capacity information. Hopefully, that helps you on your journey to finding the correct hitch for you.
If we could make a recommendation of a hitch you might want to use depending on whether or not you can use a hitch and what class you really need for your vehicle. If it at all makes sense and is safe for you to use Weigh-Safe trailer hitches for your vehicle then you should. Weigh-Safe hitches make the task of weighing your cargo as easy as loading up your cargo. All you have to do is read the built-in scale that tells you if you are overweight or underweight. Please remember that you have to factor in the weight of the driver and passengers as well. You do not want the thing that tips the scales out of your favor to be caused by an oversight.
Have a look at the Weigh-Safe hitches here. Hopefully, you find one that will suit your needs because they are literally hitches that could save your life or someone else's life.