RS404 | Eaton / Dana-Spicer Rear-Rear Differential — Remanufactured by DPX (40K GAWR)
The RS404 rear-rear tandem axle differential for Class 8 trucks is built for dependable torque delivery and long service life at 40,000 lb GAWR. Remanufactured in Mansfield, Ohio by Discount Parts Exchange - DPX with matched hypoid gearing and verified setup for gear pattern, backlash, and bearing preload. Also referenced as RS-404 or RS404-RR.
Pairs with the DS404 forward (front) differential to form a complete tandem set.
Summary
Professionally remanufactured RS404 rear-rear carrier with matched ring & pinion. Rebuilt to your exact ratio. Sold on exchange by Discount Parts Exchange - DPX.
Specs & Features
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Position: Rear-rear (tandem)
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GAWR: 40,000 lb
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Ring Gear: Hypoid, 15.4–15.7″ OD (15.5″ nominal)
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Axle Shaft Splines: 41
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Pinion Spline: 39 (1.95″ involute)
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Pinion Nut P/N: 127589
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Side Gear P/N: 127368
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Axle Housing Fastener Kit P/N: 512087
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Weight: ≈318 lb
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Recommended Lubricant: Spicer FE 75W-90 synthetic (meets Dana SHAES 256 Rev E, Dana SHAES 429, API GL-5 & MT-1, SAE J2360, Detroit DFS93K219.01, Mack GO-J Plus, Meritor O76-N, Navistar MPAPS B-6821)
Available Gear Ratios & Part Numbers (RS404 Rear-Rear)
Original kit numbers shown in parentheses where applicable.
RS404 Rear-Rear Gearsets
| Ratio |
Kit P/N |
Ring Gear P/N (teeth) |
Pinion P/N (teeth) |
| 2.64 |
211478 |
127380 (37) |
127420 (14) |
| 2.85 |
211479 |
127381 (37) |
127421 (10) |
| 2.93 |
509424 |
129534 (41) |
129533 (14) |
| 3.08 |
513373 (211480) |
127381 (37) |
139737 (12) |
| 3.25 |
513372 (211481) |
127382 (39) |
130127 (12) |
| 3.36 |
513371 (211482) |
127381 (37) |
130128 (11) |
| 3.42 |
504055 |
134325 (41) |
134326 (12) |
| 3.55* |
513370 (211483) |
127382 (39) |
130129 (11) |
| 3.70 |
513369 (211484) |
127381 (37) |
130130 (10) |
| 3.90 |
513368 (211485) |
127382 (39) |
130131 (10) |
| 4.11* |
513367 (211486) |
127381 (37) |
130132 (9) |
| 4.33 |
513366 (211487) |
130200 (39) |
130133 (9) |
| 4.63 |
513365 (211488) |
130194 (37) |
129748 (8) |
| 4.88 |
513364 (211489) |
130195 (39) |
129750 (8) |
| 5.29 |
513363 (211490) |
130194 (37) |
129818 (7) |
| 5.57 |
513362 (211491) |
130195 (39) |
129822 (7) |
| 6.17 |
513361 (211492) |
127383 (37) |
129844 (6) |
| 6.50 |
211493 |
127384 (39) |
127435 (6) |
| 7.17 |
211494 |
127385 (43) |
127436 (6) |
*Field-favorite linehaul ratios.
Note: Availability varies. Please call to confirm ratio before ordering.
What’s Included
- Remanufactured RS404 rear-rear carrier assembly (rebuilt to your requested ratio) by Discount Parts Exchange - DPX
- 12-month, unlimited-mileage parts-only warranty
- DPX tech support during install and initial run-in
Core Exchange Policy
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Required: Like-for-like, complete, rebuildable core
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Deductions may apply for: Cracked housings; burnt/missing internals; low-lube or water damage; non-matching cores
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Preparation: Core must be drained and palletized for pickup
Shipping Policy
- Ships via LTL motor freight to verified commercial addresses only
- No residential delivery — forklift or dock required at delivery
Image Disclaimer
Photos show a representative RS404 unit; final appearance may vary by ratio and casting.
Warranty
Discount Parts Exchange - DPX warrants this product against defects in materials and workmanship for 12 months from the date of shipment (parts only; no labor).
Location & Contact
Location: Mansfield, Ohio
Call for pricing and ratio availability: 419-522-3320
Curious What a Ratio Change Will Do for Your Truck?
Use our free Road Speed Calculator to plug in your tire size, current ratio, and target speed/RPM. See exactly what a 3.55, 3.73, or 4.10 would do before you buy.
Open Road Speed Calculator →
DPX — Ohio’s Premier Heavy-Duty Drivetrain Rebuilder | Built to Perform. Trusted to Last.
Reference Documentation
For detailed exploded-view diagrams, part numbers, and service data, download the official Spicer® Drive Axles AXIP-0200-32020 Illustrated Parts List covering the DS/RS404 / D404 / D405 / D454 axle family.
📄 Download Spicer DS404 / D404 Illustrated Parts List (PDF)
