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49X Chassis

Built for the Challenge

The heavy-duty vocational frame underneath the 49X is engineered to stand up to the demands of severe service applications like construction, logging and heavy haul trucking while being lighter weight, more durable, easier to service and extremely Truck Equipment Manufacturer (TEM) friendly.

Chassis Features

Single Channel Rails

Not only does the 49X offer the industry’s first high-strength single-channel rail rated 3.8 million RBM without an insert, there’s also a new, stronger 9.5mm rail that delivers the same RBM rating as an 11mm while saving nearly 100 pounds.

Splayed Frame Rails

Splayed frame shape at the front of the chassis allows for lower engine and radiator packaging that optimizes hood slope for increased visibility and safety, as well as improved engine serviceability.

Full Parent Front Frame Rail Options

Multiple parent rail front frame extension options are available, eliminating the need for bolt-on extensions or reinforcements.

Easier Upfit

Straight frame sections begin directly behind the cab and feature a constant flange-to-flange dimension, making upfit easier.

Standard Aluminum Crossmembers

Cast aluminum forward, rear suspension and end-of-frame crossmembers are standard for applications that demand greater weight savings.

Heavy-Duty Fasteners

Phosphate-coated Class 10.9 fine-thread fasteners offer a high clamp load and don't require maintenance.

Front Tow Assembly Options

A number of towing device options mounted directly to the front frame head for incredible strength, allowing you to pull your truck free without damage.

Robust Routing and Clipping

Frame rail stand-offs keep wiring and air lines separated and away from the chassis to reduce corrosion, debris damage and diagnosis time.

49X Chassis

Power Take Offs

From snowplows and mixers to bulk haul tractors and everything in between, the wide selection of options on the 49X lets you choose the right combination of front engine PTOs – FEPTO, REPTO and transmission-mounted PTOs – so you can install the equipment you need for your application.




The 49X offers three bumper styles in various finishes and thicknesses, as well as a boxed-in bumper with an optional grille guard for logging applications. A bumper mounting position specifically designed to optimize packaging to meet bridge laws, shortening BBC to 110.8", is available.

Twin Steer Axles

Factory-installed Detroit® Twin Steer front axles are available with a 40,000-lbs rating and set-back configurations for applications such as concrete pumpers. A set-forward axle prep kit option is available.

Front Tow Devices

A number of towing device options mounted directly to the front frame head of the 49X for increased strength and durability with up to 140,000 lb tow capacity.

Tool Boxes

Durable, lightweight aluminum tool boxes are available in 18-, 24-, and 34-inch widths. All are locking and can be ordered with plain, polished or diamond plate finish covers.

Battery Boxes

Battery boxes in the 49X can be mounted between rails, inside the cab or on the frame. The frame-mounted boxes are also made from lightweight, corrosion-resistant aluminum for long life. A new two-battery option is available for additional weight savings.

Air Cleaner Options

The optional pre-cleaner removes a majority of particles out of the air before entering the primary air cleaner, extending filter life and service intervals in off-road environments.


Western Star logo that features 'Serious Trucks' in white text and a red star against a gray background.