Silverado 2500Hd Warranty

im looking at a 2006 Silverado 2500HD..Need to haul horses and was going to add a gooseneck hitch (middle of the bed). I heard that hauling trailers on the vehicle with under 12 months voids some of the warranty details. Anyone familiar with this?

I just bought a 2005 2500HD Duramax. I just read the owner's manual to research your question, and it said nothing about how much time before you tow. The manual says do not tow during the break-in period, which is 500 miles.
Frank