03–07 DODGE RAM 5.9L CUMMINS — DIFFERENTIAL & DRIVETRAIN

Dial in bulletproof reliability and confident traction on your 2003–2007 Dodge Ram 2500/3500 (5.9L Cummins). From AAM 11.5" rear to AAM 9.25" front components, CPP Diesel stocks the ring & pinions, master install kits, lockers/LSDs, U-joints, driveshafts, and heavy-duty diff covers you need for towing, work, off-road, or competition.

Browse the full DIFFERENTIAL & DRIVETRAIN category for 03–07 Cummins

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Heavy-Duty Differential Covers

• Mag-Hytec AA14-11.5 Rear Differential Cover (AAM 11.5)
• Mag-Hytec AA14-9.25-A Front Differential Cover (AAM 9.25)
• Banks 11.5/11.8 14-Bolt Differential Cover (GM & Ram)

Ring & Pinions + Master Install Kits

• Dorman 697-038 Master Install Kit (AAM 11.5 Rear)
• Dorman 697-037 Master Install Kit (AAM 9.25 Front)
• Yukon Pro Kit YGK2108 — 11.5" AAM 4.56 R&P + Master Kit
• USA Standard ZGK2113 — 11.5" AAM 4.11 R&P + Master Kit

Lockers & Limited-Slip Differentials

• Yukon Dura Grip — 11.5" AAM 30-Spline LSD
• Yukon Grizzly Locker — 11.5" AAM 30-Spline

U-Joints, Yokes & Axle Seals

• Mopar 5086665AE Front Axle U-Joint (03–09 2500/3500 4WD)
• Mopar 5102157AE Rear U-Joint (03–13 2500 / 03–12 3500)
• Dana Spicer 5006813 1485-WJ Series U-Joint
• Yukon YY-C5086696 Pinion Yoke (AAM 9.25 Front)
• Yukon YMSC1007 Inner Axle Seal (AAM 9.25 Front)

Complete Driveshafts

• Dorman 946-118 Rear Driveshaft Assembly (2003, 47RE, 140.5" WB)

Why Buy Driveline Parts from CPP Diesel?

• Platform-specific fitment: Focus on 2003–2007 Ram 2500/3500 5.9L Cummins with AAM 11.5 rear & AAM 9.25 front differentials.
• Pro-grade kits: Yukon & USA Standard gear packages pair premium bearings and the correct small parts to streamline installs.
• Heat management & capacity: Mag-Hytec & Banks covers improve cooling and serviceability with drain/fill ports.
• Trusted brands: Dana Spicer, Mopar, Mag-Hytec, Yukon, USA Standard, Dorman—and more.

Helpful Tech Notes

• Know your axles: Most 03–07 Ram 2500/3500 use AAM 11.5" rear and AAM 9.25" front. Verify before ordering, especially on swapped or modified trucks.
• Gearing for tire size: Taller tires often benefit from lower (numerically higher) ratios—e.g., 4.10 or 4.56 for heavy towing or 35″–37″ tires. Choose based on actual use, tire size, and trans gearing.
• Break-in matters: New ring & pinion sets require proper break-in and fluid changes; follow kit instructions to minimize heat and wear.
• Locker vs. LSD: Lockers (e.g., Grizzly) provide maximum traction off-road/drag; LSDs (e.g., Dura Grip) offer smooth, street-friendly traction.

Frequently Asked Questions

Which differentials are on my 03–07 Ram 2500/3500?

Most trucks use an AAM 11.5" rear and an AAM 9.25" front. Confirm by VIN lookup, axle tag, or by measuring/inspecting the cover.

Do I need a master install kit with new gears?

Yes—fresh bearings, shims, seals, and hardware are strongly recommended any time you change ring & pinion to ensure correct setup and long service life.

Locker or LSD for a daily/tow rig?

For year-round street and towing, many prefer a clutch-type LSD (e.g., Dura Grip). For maximum off-road/competition traction, a mechanical locker (e.g., Grizzly) is ideal.

What gear ratio should I pick with larger tires?

As tire diameter increases, consider moving from 3.73 to 4.10 or 4.56 to restore drivability. Match to your tire size, trans, and intended RPM at cruise.

Will upgraded diff covers help temps?

Yes—performance covers increase fluid capacity and surface area, aiding cooling and simplifying service via drain and fill ports. Always follow the cover’s fill-level guidance.

Can I reuse old bearings when changing gears?

It’s not recommended. New gears should be paired with new bearings and setup parts to prevent noise and premature wear.

Do you offer related steering/suspension parts for 03–07 trucks?

Yes—see our 03–07 Steering / Suspension section for complements like track bars, tie rods, and braces.