If you have an RS with AWD I think it comes standard with the tow package. Does your vehicle have the built in receiver and 7-pin wiring? I think the thing about the alternator I saw on the "build your own" part of the Chevy website when I was playing around with it. It's in the info for adding the tow package. If you download the Blazer brochure there is also info about towing/trailering specs where it compares models.