Description
The PAI EE06720 is the differential lockout (DCDL) body kit that rebuilds the air-operated lock mechanism on Eaton single-reduction forward (front) tandem axle differentials, replacing Eaton 34779 / 034779. When the dash DCDL switch is energized, air pressure shifts the sliding clutch to lock the wheel differential for maximum traction; this kit restores those internals so engagement and release are clean and leak-free.
Signs You Need a New Differential Lockout Body Kit
- Diff lock won’t engage when the dash switch is activated
- Diff lock stays engaged after the switch is turned off
- Audible air leak from the lockout cylinder housing
- Intermittent or delayed lock engagement
Specifications
| Manufacturer | PAI Industries |
|---|---|
| Part Number | EE06720 |
| Part Type | Differential Lockout Body Kit (DCDL) |
| Axle Position | Forward Axle (Tandem) |
| Differential Type | Single Reduction |
Cross References
This kit replaces or is equivalent to the following part numbers:
- Eaton: 34779, 034779
- Navistar (International): 266783, 266783C91
Applications
This differential lockout body kit fits the following Eaton forward (front) tandem axle differentials:
- Eaton 34DS, 38DS
- Eaton DS340, DS341
- Eaton DS380, DS380-P, DS381, DS381-P
- Eaton DS400, DS400-P, DS401, DS401-P, DS402, DS402-P
- Eaton DS451, DS451-P
Representative tandem-axle vehicles using these differentials:
- Freightliner FLD, Classic, Columbia, Cascadia, Coronado
- Kenworth W900, T600, T660, T680, T800, T880
- Peterbilt 379, 389, 386, 388, 367, 579, 567
- International 9200, 9400, 9900, ProStar, LoneStar, LT
- Mack CH, CL, Vision, Pinnacle, Granite, Anthem
- Western Star 4900, 5700XE
- Volvo VNL, VNM, VHD
How the Differential Lockout Works
Air pressure at the lockout cylinder moves a piston and shift fork, sliding a clutch collar into engagement with the differential case. With the lock engaged, both wheels on the axle turn together — maximum traction in mud, snow, or loose surfaces. When the switch is released, a return spring shifts the clutch out of engagement and normal differential action resumes.
Engage the diff lock only at low speed (under 25 mph) and never while a wheel is actively spinning — loaded engagement with one wheel spinning will chip or shear the clutch teeth. Verify your axle model and serial number before ordering.
