ARB Dana 70 / Dana 80 Air Locker Differential - RD173, High Speed, 35 Spline
RD173
The ARB RD173 Air Locker Differential is a heavy-duty selectable locking differential designed for compatible Dana 70 and Dana 80 rear axle applications using 35-spline axle shafts. Built for heavy-duty trucks, tow rigs, expedition vehicles, rock crawlers, and mixed street-and-trail builds, this high-speed Air Locker provides fully locked traction on demand. With the flip of a dash-mounted switch, compressed air activates the internal locking mechanism, forcing both axle shafts to rotate together for improved traction through rocks, mud, snow, and challenging terrain.
When activated, its patented locking mechanism provides positive mechanical engagement for demanding drivetrain loads. The heavy-duty two-piece steel carrier, forged internal components, and steel-reinforced annular air seal are engineered for strength and long-term reliability. The RD173 high-speed configuration is intended for compatible lower numerical gear ratio applications, making it a practical option for heavy-duty trucks that need dependable traction without permanently locking the rear axle.
Includes:
- (1) ARB RD173 Dana 70 / Dana 80 Air Locker Differential Assembly
- (1) Dash-Mounted Activation Switch
- (1) Air Solenoid Valve
- Air Line
- Bulkhead Fitting
Important:
- A compatible ARB Air Compressor is required for operation and is sold separately.
- Dana 80 applications require the Air Locker flange holes to be drilled or reamed to accept 9/16" ring gear bolts.
- Verify the installed Dana 70 or Dana 80 axle, 35-spline configuration, and gear ratio carrier compatibility before ordering.
Specifications
| Manufacturer | ARB |
|---|---|
| Part Number | RD173 |
| Product Type | Selectable Air Locking Differential |
| Axle Platform | Dana 70 / Dana 80 |
| Axle Position | Rear |
| Axle Spline Count | 35-Spline |
| Axle Shaft Diameter | 1.50" |
| Gear Ratio Compatibility | High-Speed / Lower Numerical Gear Ratio Applications - Verify Carrier Break |
| Carrier Compatibility | Compatible Dana 70 / Dana 80 High-Speed Carrier Configurations |
| Performance Configuration | High-Speed |
| Differential Operation | Selectable Open / Fully Locked |
| Engagement Type | Pneumatic / Compressed Air |
| Carrier Construction | Heavy-Duty Two-Piece Steel Design |
| Locking Mechanism | Patented Timed Locking Mechanism |
| Air Seal | Steel-Reinforced Elastomer-Bonded Annular Seal |
| Internal Components | Forged Alloy Steel Side Gears & Heavy-Duty Cross Shaft |
| Material | Steel |
| Finish | Silver |
| Installation Type | Differential Carrier Replacement |
| Primary Application | Dana 70 / Dana 80 Rear Axle Traction Upgrades for Heavy-Duty Trucks, Tow Rigs & Off-Road Builds |
| Required Components | Compatible Air Compressor, Air Supply, Differential Bearings & Installation Components |
| Special Installation Requirement | Dana 80: Drill or Ream Locker Flange Holes for 9/16" Ring Gear Bolts |
| Known Incompatibilities | Incorrect Spline Count, Carrier Break or Incompatible Dana 70/80 Differential Configurations |
| Quantity | One Air Locker Differential Assembly |
Fitment
The ARB RD173 is designed for compatible Dana 70 and Dana 80 rear differential applications using 35-spline axle shafts. Vehicle fitment depends on the installed axle, carrier configuration, and gear ratio.
| Make | Model | Year Range | Axle Application |
|---|---|---|---|
| Chevrolet | C3500 / K3500 | 1992–2000 | Dana 70 / 80 Rear - Verify Axle |
| Chevrolet | G30 | 1996 | Dana 70 / 80 Rear - Verify Axle |
| Dodge | B350 / B3500 | 1993–1998 | Dana 70 / 80 Rear - Verify Axle |
| Dodge | Ram 2500 / 3500 | 1994–2002 | Dana 70 / 80 Rear - Verify Axle |
| Ford | E-350 Club Wagon | 2003–2005 | Dana 70 / 80 Rear - Verify Axle |
| Ford | E-350 Econoline / Econoline Club Wagon | 1992–2002 | Dana 70 / 80 Rear - Verify Axle |
| Ford | E-350 Super Duty | 1999–2010 | Dana 70 / 80 Rear - Verify Axle |
| Ford | F-350 | 1993–1997 | Dana 70 / 80 Rear - Verify Axle |
| Ford | F-350 Super Duty | 1999–2016 | Dana 70 / 80 Rear - Verify Axle |
| GMC | C3500 / K3500 | 1992–2000 | Dana 70 / 80 Rear - Verify Axle |
Fitment Notes:
- Fits compatible Dana 70 and Dana 80 rear differential applications using 35-spline axle shafts.
- High-speed carrier configuration intended for compatible lower numerical gear ratios.
- Verify the exact carrier break and ring gear compatibility before ordering.
- Dana 80 applications require the Air Locker flange holes to be drilled or reamed for 9/16" ring gear bolts.
- Not every vehicle listed uses a Dana 70 or Dana 80 rear axle.
- Verify axle identification, spline count, carrier bearings, and ring gear mounting dimensions before installation.
- Requires a compatible compressed air supply.
- ARB air compressor sold separately.
- Professional differential installation is recommended.
Builder Note: Dana 70 and Dana 80 rear axles were used in multiple heavy-duty truck configurations with different axle shafts, gear ratios, and differential carriers. The RD173 should be selected based on the installed axle and carrier specifications rather than vehicle year alone. For Dana 80 builds, account for the required ring gear bolt hole modification before final differential assembly.
FAQ
What axles does the ARB RD173 Air Locker fit?
The RD173 is designed for compatible Dana 70 and Dana 80 rear axle applications using 35-spline axle shafts. Exact fitment depends on the differential carrier, gear ratio, and axle configuration.
Will the ARB RD173 fit my Ford F-350 or Dodge Ram 3500?
The RD173 is listed for select Ford F-350 and Dodge Ram 3500 applications equipped with compatible Dana 70 or Dana 80 rear axles. Verify the installed axle model and spline count before ordering because different rear axle options were available.
What gear ratios are compatible with the RD173?
The RD173 is identified as a high-speed Air Locker intended for compatible lower numerical gear ratio carrier configurations. The exact carrier break should be confirmed with ARB before ordering.
What does high-speed mean on an ARB Air Locker?
ARB uses high-speed and low-speed designations to distinguish certain differential carrier and gear ratio configurations. High-speed generally refers to the carrier configuration associated with lower numerical gear ratios, not a vehicle's maximum operating speed.
Does the RD173 require modifications for a Dana 80 axle?
Yes. The supplied installation information specifies that Dana 80 applications require the Air Locker flange holes to be drilled or reamed to accept 9/16" ring gear bolts. This modification should be performed using the correct machining procedures and verified before final assembly.
Does the ARB RD173 require an air compressor?
Yes. A compatible ARB air compressor and air supply system are required to activate the locking mechanism. The compressor is sold separately.
How does the ARB RD173 Air Locker work?
Compressed air activates the internal locking mechanism, preventing the rear axle shafts from rotating independently. When engaged, both rear wheels rotate together for maximum available traction. When disengaged, the differential operates as a conventional open unit.
Can the RD173 be used in a daily-driven or towing truck?
Yes. The selectable design allows normal differential operation when disengaged, making it suitable for compatible trucks that see both street and off-road use. The locker does not increase the vehicle's factory towing or axle load ratings.
What is the difference between the ARB RD173 and RD176?
The RD173 is a 35-spline high-speed Air Locker for compatible Dana 70 and Dana 80 applications. The RD176 is a 40-spline low-speed performance Air Locker intended for custom Dana 70X and Dana 80X axle builds. The two models have different spline and carrier requirements and are not interchangeable.
Does the RD173 include the activation switch and air line?
Yes. The supplied kit contents include the Air Locker differential assembly, activation switch, solenoid valve, air line, and bulkhead fitting. The compressor is sold separately.
Can the RD173 be installed during a ring and pinion gear change?
Yes. Installing an Air Locker during a differential re-gear is practical because the original carrier is already being removed. Proper carrier bearing preload, backlash, and ring gear tooth contact pattern must be established during installation.
What should I verify before ordering the RD173?
Confirm the Dana 70 or Dana 80 axle platform, 35-spline axle shafts, high-speed carrier compatibility, ring gear mounting dimensions, and required air supply. Dana 80 applications also require confirmation of the 9/16" ring gear bolt modification.