I have a 2004 Chevrolet Silverado brochure in front of me, and according to it you can configure a new 1500
("1/2 ton") to tow a trailer up to 9200 lbs. This would be for a regular cab, 4X4 with the 5.3 automatic and 4.10 rear end.
The 6.0 appears to be available only in the all wheel drive "SS" model, and that as a special high output version; this according to the brochure - but see below.
Of course, what you really need is the GCWR, which appears to be available only in the owner's manual - perhaps it is expected that you buy the truck before this can be revealed. The greatest GCWR in the 1500
series is 16,000 lbs., which requires the 6.0(!). So, is it available or not?
The trailering capacity is probably calculated by taking the empty weight of a base model (4,100 to 5,200 lbs. plus options, depending upon the configuration) plus a driver and subtracting that from GCWR.