2003 GMC Sierra Owner Manual M Please keep this manual in your vehicle, so it will be are shown along with the text describing the operation. This manual includes the latest information at the time it was printed. We reserve the right to make changes after that time without further notice. For Manuals and operating instructions for this GMC vehicle We have the following 2003 GMC Sierra 1500 Pickup manuals available for free PDF download. You may2003 GMC Sierra owners manual free download in PDF format or simply view it online. of the Owner's Manual. The weight of passengers, cargo and options or accessories may reduce the amount you can tow. Requires Sierra 3500 HD Regular Cab