Does anyone now what this means? (gross trailer weight braked (lbs) 6,400) I have been trying for two days to find out what my max towing capacity is on my '06 sierra, with the 4.8L, automatic truck has and I came across this on the GMC website. I even asked the dealer today and they could only tell my my curb weight of my truck (3,233lbs). I hope this will be part of my equation to figure out what I can tow effectively. Thanks.