Western Star 49X

The 49X is Western Star’s Class 8 vocational truck and tractor, which its model page calls a “Vocational Truck Tractor”. Western Star Trucks Sales, Inc., a subsidiary of Daimler Truck North America, lists it beside the 47X and the 49X Power Hood and describes it as “The toughest and most advanced heavy duty truck in the industry.” This page is built from eight undated pages of westernstartrucks.com, read on 4 November 2026: the 49X model page with its specifications list, the 49X powertrain and chassis pages, the general powertrain page, and the X-Series cab, chassis, interior and upfit pages. The US weight classes are explained in GVWR, GCWR and GAWR.

Overview

Western Star says the 49X is “Engineered for the demands of Class 8 vocational work”, for applications “ranging from construction, logging, oilfield, to over the road hauling”. It belongs to the X-Series; Western Star’s cab, chassis, interior and upfit pages describe the series as a whole, and the interior and upfit pages name both the 47X and the 49X.

The optional Power Hood, a separate entry in Western Star’s menu as the “49X Power Hood”, is available for the set-forward axle configuration. Western Star says it is “purpose-built to support larger radiator packaging for high-output engines, including DD15 and DD16”, for applications that require the highest gross combined weight limits, such as heavy haul and oil field work.

No document opened gives a launch date, a production site, earlier generations of the model, overall dimensions, a wheelbase, a kerb weight or a gross vehicle or combination weight rating for the 49X. Western Star says that all X-Series technical details are in its Technical Resource Guide, for which it directs readers to log onto DTNAPortal.com.

Cab and hood

Western Star describes the X-Series cab as “Constructed from a premium-grade aluminum and enhanced with steel reinforcements”, naming reinforcements at the backwall header, B-pillars and hinges and an A-pillar of increased section size and strength. The steel door is an integral part of the cab structure and hangs on internally mounted forged steel hinges, with a 70-degree opening angle; the steps are aluminium with volcano tread. The composite trench-style low roof has a lowered centre section for packaging equipment over the cab. A Quiet Steel engine tunnel and vocationally tuned cab isolators are listed for noise and ride.

The one-piece, roped-in windshield has standard solar-tinted glass and 24-inch wiper blades that cross over the centre of the glass; impact-resistant and heated windshields are optional. The cab page lists a standard single rear window, an optional solid wall and an optional three-piece rear window, which it says “increases the rear window area by 77% over previous models”, with impact-resistant polycarbonate also offered; the 49X list gives “Optional single or high-visibility three-piece rear window”. The C-bar mirrors are mounted to steel door reinforcements, with standard heating and optional turn signals in the lower convex mirror. The dual-stage LED headlights have polycarbonate lenses with a hard coating, optional heat grids and amber daytime running lights that double as turn signals.

The hood is moulded resin with a sloped design; Western Star says the X-Series hoods are “nearly 100 pounds lighter than their previous comparable hoods”. It sits on the ISO Tech hood suspension, has a standard locking strut and opens to 70 degrees. The fenders are steel-reinforced moulded resin. The 49X list gives a “Radiator-mounted steel grille with stainless steel surround”; the cab page says the grille “is made from a single piece of stainless steel”. The aluminium radiator is standard, with an optional protection package of a top guard and rear rock screen. Dual stainless steel air intake covers feed an underhood air cleaner, for which Western Star claims “nearly the same dust capacity as twin external canister air cleaners with 60 percent less weight”; a hood-mounted pre-cleaner and a left-side access hatch are optional, and the hood has structural provisions for auxiliary mirrors.

Sleepers and interior

Western Star’s interior page refers to day cabs and sleepers, and lists four sleepers as available on both the 49X and the 49X Power Hood: the 36-inch Trench Style Low Roof, the 48-inch and 60-inch Mid Roof and the 72-inch Stratosphere Roof. The optional Driver’s Lounge is listed for a 60-inch Mid Roof, a 72-inch Mid Roof or a 72-inch Stratosphere High Roof, with an optional driver’s loft whose two-seat dinette/worktable folds flat into a Murphy-style bed, and a swivelling bracket for a TV of up to 26 inches. The sleepers come with a single bed or dual bunks, the latter with a telescoping ladder rated at 400 lb, and wardrobe, microwave and refrigerator cabinets. The 60-inch and 72-inch sleepers can have windows of 31.5 by 22 inches. Espar and Webasto heaters, premium and extreme-climate insulation and factory-installed inverters or inverter pre-wiring are optional. Cab types in general are covered in truck cabs explained.

The HVAC system has 5 face outlets, 4 floor outlets, 2 side window defrost outlets and 10 blower speeds. Sleepers can have an optional idle-free, battery-operated dual HVAC system that provides up to 10 hours of cooling or 34 hours of heating when parked.

The cab has a wing dash layout. The Driver Command Center has six gauges and a central LCD screen showing engine information and alerts from Detroit Assurance and Detroit Connect Virtual Technician, and each X-Series truck has a standard 7-inch interactive touch screen. The leather-wrapped steering wheel carries controls for the stereo, the Driver Command Center and cruise control, with a Bluetooth connection for mobile phones; the steering column is fully adjustable, and a control stalk handles automated manual and automatic transmission shifting and engine braking. The programmable rocker switches are backlit with laser-etched graphics and guards. There are three cup holders, and the FlexPanel takes body controls, tablet devices, up to 24 switches or up to 10 gauges.

Engines

Western Star’s three lists agree on the Cummins X15 and give different ratings for the other four engines:

The general powertrain page names “The new Detroit Gen 6 DD13, DD15, and DD16 engines”, marks the DD16 “Gen 6 coming in 2028”, and lists the Power Hood as available with the DD15, DD16 and X15 and not with the DD13 or X12. Western Star says it provides engines “compliant with EPA, CARB emissions, GHG, and OBD requirements”. No Western Star document opened gives kilowatt or newton-metre figures, cylinder counts or rated speeds for these engines; how such ratings are read is covered in reading truck power figures.

The 49X powertrain page says the DD13 has been “significantly redesigned with vocational jobs in mind”, with vocationally focused ratings, a thermal control valve, front and rear engine power take-offs, and high compression ratios. For the DD15 it lists a ball bearing turbocharger, reduced idle speed and a piston design with increased compression and improved swirl combustion. It calls the DD16 “The biggest, toughest and most powerful engine Detroit has ever produced” and “the only 16-liter engine available”, and says the X12 weighs 2,050 pounds, 600 pounds less than its predecessor. The DD13 and DD15 also appear on the Freightliner Cascadia page.

Transmission

The 49X specifications list gives the Detroit DT12-V and DT12-VX, the Allison 4000, 4500 and 4700 automatics, Eaton Fuller manual gearboxes with 10, 13 or 18 speeds together with the 8LL and 9ALL, and the Eaton Endurant automated gearbox with 12 or 18 speeds. The 49X powertrain page adds the DT12-HE; the general powertrain page has no DT12-HE row.

For the DT12-V and DT12-VX, Western Star lists a wider overall ratio with a new planetary gear set, a Rock-Free Mode, an Off-Road Mode with its own shift maps, a Paver Mode that shifts from Neutral to Drive without the brake pedal, a bottom power take-off that can run together with the rear one, and a Power Launch that raises engine speed up to 1,200 rpm during launch. Automated gearboxes in general are covered in automated manual transmissions.

Axles, suspension and brakes

Western Star says the Meritor P600 planetary axle is available in tandem or tridem configurations for heavy-haul applications “with GCWs of 200,000+ lbs.” The factory-installed Detroit Twin Steer front axles have a 40,000 lb rating and set-back configurations for applications such as concrete pumpers, and a set-forward axle prep kit is available. No Western Star document opened prints a list of wheel formulas for the 49X; the notation is explained in axle configurations.

The brakes are air disc brakes with a WABCO 4S/4M or 6S/6M anti-lock braking system, with or without traction enhancement.

Frame and chassis

The 49X specifications list gives single-channel rails at “1.8-3.8MM inch-lbs” RBM and inner C-channel reinforced rails at “4.4-5.5MM inch-lbs” RBM, with parent-rail front frame extensions of 8 to 30 inches. The 49X chassis page calls the single-channel rail rated at 3.8 million RBM without an insert “the industry’s first” of its kind, the X-Series chassis page “the industry’s only”; both also describe a 9.5 mm rail with the same RBM rating as an 11 mm rail, saving nearly 100 pounds. The frame is splayed at the front to lower the engine and radiator, its straight sections begin directly behind the cab with a constant flange-to-flange dimension, and it has standard cast aluminium forward, rear-suspension and end-of-frame crossmembers, phosphate-coated Class 10.9 fine-thread fasteners and stand-offs that keep wiring and air lines away from the rails.

Western Star lists three bumper styles and a boxed-in bumper with an optional grille guard for logging, all tapered at the wheel ends: a standard 1/8-inch stainless steel vocational bumper, and optional 3/16-inch painted steel, 1/4-inch plain or polished aluminium, 5/16-inch bright steel severe-service, 3/8-inch painted steel severe-service and 1/4-inch painted or bright steel logger bumpers. A bumper mounting position designed for bridge laws shortens the bumper-to-back-of-cab dimension (BBC) to 110.8 inches. The front tow devices are mounted directly to the frame head: dual removable tow hoops and a centre tow pin at 80,000 lb, and a high-capacity centre tow pin at 140,000 lb. Aluminium tool boxes come in 18-, 24- and 34-inch widths. The standard battery box sits inside the cab under the passenger seat; boxes can also be mounted between the rails or on the frame, and a two-battery option is available.

Fuel and DEF tanks

The fuel tanks are 25-inch cylindrical aluminium tanks, plain or polished. Western Star gives “LH 60-150 gallon (227-568 liter)” and “RH 60-, 70-, 80-, 100-, 120-, 150-gallon (227-, 265-, 303-, 379-, 454-, 569-liter)”, with forward mounting as standard and aft mounting as an option, split fuel and hydraulic tanks on either side, and auxiliary fuel supply and return ports. The upfit page adds rectangular left-hand tanks of 60, 80 and 90 gallons with raised mounting for belly plow applications. The DEF tanks are given as “8-, 13- and 23-gallon (23-, 49- and 87-liter)”, mounted forward as standard, with left or right aft mounting as an option.

Power take-offs and upfit

Front engine power take-offs (FEPTO), rear engine power take-offs (REPTO) and factory-installed transmission power take-offs are available; with a power take-off engaged, the Driver Command Center shows engine speed presets, and the steering wheel buttons change engine speed. Western Star says the X-Series was designed for body upfit by truck equipment manufacturers (TEMs) on applications including dump trucks, concrete mixers and cranes. The mid-chassis packaging, which it says delivers a clear back of cab, includes forward-mounted DEF tanks, a battery box inside the cab, air tanks that can be mounted in several positions and are available in aluminium, an updated air dryer position, and factory-installed split hydraulic and fuel tanks.

QuickFit, which Western Star calls “a fully integrated upfit solution”, provides dedicated connection points and factory-installed switches and indicators. An auxiliary E-Vault mounted on the backwall inside the cab holds QuickFit connectors, a powertrain interface connector, body lighting interface connectors, a TEM-specific power distribution module and high-current power access. Western Star’s CHEC Tool is the interface to the X-Series programmable controllers, with which TEMs and dealers view and change electrical configurations. QuickFit Dash Access, on top of the dash, routes wires to dash-mounted devices. Western Star says Detroit Connect “translates the performance data of any type of truck into real-time information”.

Safety and driver-assistance systems

With Detroit engines, the specifications list gives the Detroit Assurance suite: Active Brake Assist 5, Adaptive Cruise Control to 0 mph, Side Guard Assist, Tailgate Warning, Lane Departure Warning, automatic headlights and wipers, Intelligent High Beams, Brake Hold Mode, Traffic Sign Display and Active Speed Intervention. With Cummins engines, WABCO OnGuard with collision mitigation and adaptive cruise control is optional. Western Star calls Detroit Assurance “the most advanced suite of active safety systems ever offered to the vocational market”.

The model page says Active Brake Assist 5 detects distance and speed to moving and stationary objects and recognises pedestrians about to cross the truck’s path, alerting the operator while partially braking, followed by full braking if the operator does not react. It describes a Side Guard Alert that detects objects on the passenger side and alerts the operator. Adaptive Cruise Control to 0 mph and Brake Hold Mode, which keeps the truck stopped when the driver’s foot leaves the brake pedal, are given as working with the DT12 transmission.

All X-Series trucks have a standard relocatable backup camera, on the rear end of the frame or, on tractors, at the top of the cab backwall; it can be ordered with 10 additional feet of cable. Up to 3 additional cameras can be added on the grille and on the right and left sides of the cab, and all four views can be shown at once on the touch screen. The backup view appears automatically in reverse, and the side views with the corresponding turn signals.

Source notes

Engines, in the maker’s units, on the 49X specifications list: Detroit DD15, 400-505 hp and 1,550-1,850 lb-ft; Detroit DD16, 500-600 hp and 1,850-2,050 lb-ft; Cummins X12, 350-500 hp and 1,450-1,700 lb-ft; Cummins X15, 400-605 hp and 1,450-2,050 lb-ft. The 49X powertrain page adds the Detroit DD13, 12.8 l, 370-525 hp and 1,250-1,850 lb-ft, and gives the DD15 (14.8 l) 425-505 hp, the DD16 15.6 l, the X12 (11.8 l) 1,250-1,700 lb-ft and the X15 14.9 l. Western Star’s general powertrain page gives the DD13 at 410-525 hp and 1,450-1,850 lb-ft, the DD15 at 425-505 hp and 1,650-1,900 lb-ft, the DD16 at 560-605 hp and 1,850-2,050 lb-ft with Gen 6 coming in 2028, and the X12 at 1,200-1,700 lb-ft. Gearboxes: Detroit DT12-V, up to 2,250 lb-ft and 160,000 lb GCW; Detroit DT12-VX, up to 2,500 lb-ft and 275,000 lb GCW, application approval required over 160,000 lb; Detroit DT12-HE on the 49X powertrain page, up to 2,250 lb-ft and 160,000 lb GCW; Eaton Fuller, 1,450-2,050 lb-ft and 170,000 lb GCW; Allison 4000, 4500 and 4700, 1,250-1,850 lb-ft and 170,000 lb GCW. Front axles: Detroit and Meritor single steer 12,000-23,000 lb GAWR, Detroit tandem steer 36,000-40,000 lb GAWR. Rear axles, GAWR: Detroit single 23,000 lb, tandem 40,000-46,000 lb; Dana tandem 46,000-60,000 lb; Meritor single 21,000-30,000 lb, tandem 40,000-58,000 lb, tridem 69,000-78,000 lb, planetary 84,000-126,000 lb; Sisu planetary 70,000-105,600 lb. Front suspension: flatleaf 14,600-23,000 lb, taperleaf 12,000-20,000 lb. Rear suspension: AirLiner single 21,000-23,000 lb, tandem 40,000-46,000 lb, tridem 69,000 lb; Chalmers tandem 40,000-70,000 lb; flatleaf single 23,000-30,000 lb; Hendrickson tandem 40,000-52,000 lb; Neway single 26,000 lb, tandem 46,000-52,000 lb, tridem 69,000-78,000 lb; TufTrac tandem 40,000-52,000 lb. Frame: single-channel rails at 1.8-3.8 million inch-lb RBM, inner C-channel reinforced rails at 4.4-5.5 million inch-lb RBM, a 9.5 mm rail with the RBM rating of an 11 mm rail, Class 10.9 fasteners, parent-rail front frame extensions of 8 to 30 in, and a bumper position shortening BBC to 110.8 in. Front tow devices of 80,000 and 140,000 lb. Fuel tanks: 25 in cylindrical aluminium, 60-150 US gallons, printed as 227-568 l on the left and 227-569 l on the right. DEF tanks: 8, 13 and 23 US gallons, printed with 23, 49 and 87 l. Sleepers: 36 in low roof, 48 and 60 in mid roof, 72 in Stratosphere roof. Western Star’s X-Series pages describe the series as a whole; the interior and upfit pages name both the 47X and the 49X. No document opened gives a launch date, overall dimensions, a wheelbase, a wheel formula, a kerb weight or a gross weight rating for the 49X.