Medium Duty 340

The Peterbilt 340 is a Class 7 and 8 vocational truck, designed for demanding applications that require durability, maneuverability, and customization. Positioned just above the 335 in terms of vocational capability, the 340 is built for heavier-duty roles and is commonly spec’d with tandem axles, higher GVWRs, and a wide variety of body types.

The Peterbilt 340 is frequently used for:

• Dump trucks and construction
• Concrete mixers
• Vacuum and tank trucks
• Roll-off containers
• Utility service and crane bodies
• Heavy municipal and fire/rescue applications

With its higher-rated chassis and robust spec options, the 340 is ideal for operators who need a vocational workhorse without stepping into full highway tractor territory.

Cab Type:

The 340 uses Peterbilt’s 1.9-meter narrow cab (same platform as the 325–337). Though vocational in size, the cab offers solid driver visibility and comfort, and supports trim upgrades like air ride seats, tilt steering, and overhead storage.

Aftermarket Seat Compatibility:

The 340’s 1.9-meter cab features the standard vocational seat bolt pattern—approximately 4.68" x 12". This makes it broadly compatible with many aftermarket seats, especially those built for vocational trucks.

Recommended aftermarket seats for the Peterbilt 340:

• Knoedler Harrier – low-profile option and great for vocational cabs

• National Corsair or Ensign – bolt-in or adaptor-ready for most vocational cabs

• Bostrom Wide Ride Core or T-Series – may need a low-profile base or shim/adaptor

Installation Notes:

• Most vocational-style seats bolt in directly.

• If the truck has in-cab HVAC, storage boxes, or battery trays, these may limit seat base height or mounting options.

• Taller or wider seats may reduce clearance or limit travel range—low-profile suspensions are best in the 340 cab