Here is a link to the origional Chevy brochure for a 1995. Im guessing the tow rating would be the same or at least close for other years. The brochure is for a Canadian truck but it is still usefell and neat to look at. See the links below.
Towing Info
http://www.lov2xlr8.no/brochures/che.../bilder/20.jpg
The whole brochure
http://www.lov2xlr8.no/brochures/chevy/95ch/95ch.html