In the case of the 00-07 GMs, an aftermarket hitch is waaay better than the factory one. As was pointed out, the "towing package" is not just the hitch, but the wiring for lights and brakes, along with a power steering cooler, engine oil cooler, and additional transmission cooler. Depending on the vehicle, it may already have and/or not need additional cooling capabilities. If you can provide specifics you will get more detailed replies.