Peterbilt 357/378 Deck Plates & Air Line Boxes

Frequently Asked Questions About Peterbilt 357/378 Deck Plates & Air Line Boxes

What are deck plates and air line boxes used for on a Peterbilt 357/378?

Deck plates are the flat, often diamond-plate panels that sit behind the cab on the frame rails, providing a durable walking and mounting surface while covering the frame structure. Air line boxes are mounted on or near the deck plate area and house the air and electrical lines that run between the tractor and trailer, keeping them organized, protected, and easy to access for hookups and inspections.

Will these deck plates and air line boxes fit my specific Peterbilt 357 or 378?

Fitment can vary depending on your truck's frame width, wheelbase, and factory configuration, so it's important to check the listed specifications and part numbers against your VIN or existing components before ordering. If you're unsure, our team can help confirm compatibility so you get a proper fit the first time.

What materials and finish options are available?

Most deck plates and air line boxes are offered in aluminum or steel, with aluminum being popular for its lighter weight and natural corrosion resistance. Finishes typically include mill (raw) aluminum, polished aluminum for a bright, chrome-like look, and painted or powder-coated steel options depending on the specific product.

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

Installation generally involves unbolting the old unit from the frame rail and mounting the new one using the existing bolt pattern, though some jobs may require drilling or minor bracket adjustments if the replacement part differs slightly from the original equipment. Most experienced techs or shop mechanics can complete the swap with basic hand tools in a reasonable amount of time.

How do I keep a polished aluminum deck plate or air line box looking good over time?

Regular washing and periodic polishing will help maintain the shine and prevent oxidation, especially since this area is exposed to road grime, salt, and moisture. Applying a quality aluminum polish or protectant on a routine basis will extend the life of the finish and keep it looking like new.