GMC General Truck Deck Plates & Air Line Boxes

Frequently Asked Questions About GMC General Truck Deck Plates & Air Line Boxes

What are deck plates and air line boxes used for on a GMC General?

Deck plates and air line boxes are mounted behind the cab of the truck to organize and protect the electrical cables and air lines that run between the tractor and trailer. The deck plate provides a flat mounting surface on the back of the cab, while the air line box houses and shields the glad hands and electrical cord from road debris, moisture, and physical damage during coupling and everyday operation.

Will this deck plate or air line box fit my specific GMC General model year?

Fitment can vary depending on the cab configuration and frame setup of your specific GMC General, so it is important to check the listed year range and specifications on each product page before ordering. If you are unsure about compatibility, comparing your truck's existing hardware and mounting points to the product dimensions listed, or contacting our sales team with your VIN or truck details, will help confirm a proper fit.

What material are these parts made from, and how well do they hold up?

Most deck plates and air line boxes are constructed from steel or aluminum, depending on the manufacturer and model. Steel versions typically offer added durability and rigidity, while aluminum options provide corrosion resistance and a lighter overall weight. Many are available in raw, painted, or polished finishes, so you can choose an option that matches your truck's appearance and your maintenance preferences.

How difficult is it to install a new deck plate or air line box?

Installation generally involves removing the old unit and bolting the new one into the existing mounting holes on the back of the cab, though some setups may require minor drilling or adjustment depending on the part and your truck's configuration. Most drivers and shop technicians familiar with basic hand tools can complete the swap, but if your truck has custom modifications or non-standard mounting points, professional installation is recommended.

Can I replace just the air line box without replacing the entire deck plate, or vice versa?

In many cases, yes. Air line boxes and deck plates are often sold as separate components, so if only one part is damaged or worn, you can typically replace just that piece rather than the entire assembly. That said, it is a good idea to inspect both components at the same time, since they are exposed to similar wear from weather and road conditions, and replacing them together can help avoid a second service interruption down the road.