The Dana Spicer DD404-390 is a tandem-drive axle differential designed for demanding heavy-duty truck applications. Known for its reliability, strength, and ease of service, the DD404 is ideal for fleets requiring consistent performance, high load capacity, and a low cost of ownership.

Built with hypoid gearing for quiet and efficient operation, the DD404 features a double-drive configuration—meaning both axles are powered—providing increased traction and performance in both highway and vocational settings. With a gross axle weight rating (GAWR) of 40,000 lbs, this axle is built to endure high-stress conditions including linehaul, construction, and refuse operations.

Thanks to its modular carrier design, wide gear ratio options, and compatibility with common suspension systems, the DD404 remains a popular, versatile solution for truck OEMs and aftermarket fleets alike.

Technical Specifications

General Features:

Double-drive tandem axle for heavy-duty truck applications
Designed for on-highway and vocational use
Proven hypoid gear design for quiet operation and durability

Axle Rating & Load Capacity:

Gross Axle Weight Rating (GAWR): 40,000 lbs (18,144 kg)
Ideal for Class 8 trucks and severe-service environments

Gear Design and Ratios:

Gear Type: Single-reduction, hypoid gearing
Ring Gear Diameter: 15.25 inches (387 mm)
Input Shaft Spline Count: 39-spline (standard)
Available Gear Ratios:
- 3.08, 3.21, 3.36, 3.55, 3.70, 3.90, 4.10, 4.33, 4.63, 4.88, 5.29

Construction and Materials:

Carrier Housing: Cast ductile iron for strength and heat dissipation
Heat-treated alloy steel gears for long service life
Rugged, high-strength axle shafts for durability under high load

Lubrication and Cooling:

Integrated pressurized lubrication system for efficient oil flow
Optional lubrication pump available for extended service cycles
Oil Capacity: Approx. 16–18 quarts per axle (depending on housing and configuration)

Differential Lock and Traction:

Standard inter-axle differential (power divider) for torque distribution
Optional driver-controlled differential lock for improved traction in off-road or slippery conditions

Suspension & Brake Compatibility:

Compatible with multiple suspensions: air ride, leaf spring, walking beam
ABS sensor-ready hub options available
Multiple track widths and housing configurations available for OEM flexibility

Serviceability and Maintenance:

Modular carrier design simplifies removal and servicing
Commonality with Dana 404-family components reduces parts inventory needs
Designed for long service intervals and ease of maintenance

Applications:

Freight and linehaul trucks
Refuse and sanitation vehicles
Dump and construction trucks
Logging and forestry operations
General vocational applications

Key Benefits:

Reliable, proven 40,000 lb GAWR performance
Quiet and efficient hypoid gear operation
Wide ratio range allows performance and fuel economy optimization
Easy service and low downtime with modular carrier design
Trusted by OEMs and fleets across North America

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Weight	9 lbs
Category	Differential & Axle
Subcategory	Housings

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