Freightliner Century 112/120 Deck Plates-Air Box

Frequently Asked Questions About Freightliner Century 112/120 Deck Plates-Air Box

What exactly is a deck plate and air line box on a Freightliner Century?

The deck plate is the flat panel located behind the cab on the frame rail, commonly used as a step or work surface, while the air line box (or air box) is the housing that organizes and protects the air lines and electrical lines running between the tractor and trailer. On the Century 112/120, these components are often combined into a single assembly mounted at the back of the cab.

Will this deck plate or air box fit both the 112 and 120 Century models?

Most deck plates and air boxes designed for the Century line are built to fit both the 112 and 120 models since they share the same frame width and mounting points behind the cab. However, always check the listing description and measurements against your truck's specific setup, especially if your truck has aftermarket modifications or a non-standard frame configuration, since production years can bring slight variations.

What material are these deck plates and air boxes made from, and how well do they hold up?

These parts are typically made from aluminum or steel. Aluminum options resist rust and are lighter, which is a common preference for owners looking to reduce weight and avoid corrosion, while steel versions tend to be more rigid and budget-friendly but require a protective finish to prevent rust over time. Check the product listing for the specific material and any coating or finish applied before purchasing.

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

Installation generally involves unbolting the damaged or worn unit from the frame and mounting the replacement using the existing bolt holes. Most owners with basic hand tools can complete the swap without specialized equipment, but you will need to disconnect and reconnect the air lines and any electrical connections housed in the box, so take care to label lines before removal to avoid confusion during reassembly.

How do I know if I need a new deck plate/air box versus a repair?

If the plate is cracked, heavily rusted through, or the air box no longer holds its lines securely, a full replacement is usually the more reliable option rather than patching it. Minor surface rust or cosmetic wear can often be cleaned up and repainted, but structural damage or broken mounting points typically mean it is time to replace the unit to avoid air line damage or safety issues on the road.