2004.5-2007 Dodge 5.9L Cummins Differential Parts

Differentials on the 2004.5-2007 RAM 5.9L Cummins

American Axle builds both ends of these trucks. On 4x4s, the front is an AAM 9.25-inch, 33-spline axle; the Dana 60 front was used only through 2002. The 3500 and heavier-duty 2500 configurations carry the AAM 11.5 rear with an 11.50-inch ring gear, 30-spline full-floating shafts and ratios of 3.42, 3.73 or 4.10. The 11.5 cover uses 14 bolts torqued to 43-62 ft-lb and seals with a reusable rubber gasket, which keeps a fluid change on the 5.9L Cummins trucks simple.

Fluid and service

The front differential takes 2.45 qt of 75W-90 GL-5 synthetic. The AAM 11.5 rear takes 3.8-4.2 qt of 75W-90 or 75W-140; if your axle turns out to be an AAM 10.5, it takes 2.65 qt. The maintenance schedule calls for a differential fluid change every 15,000 miles under severe service, and 75W-140 synthetic is the heavy-towing grade for the 11.5.

Stock cover or aftermarket

For a truck that rarely pulls a load, the factory cover and gasket are fine to reuse at a fluid change. If you tow, a finned or deep aluminum cover adds fluid capacity, which is the main reason to make the swap. Check each product page for the added capacity so you know how much oil to buy.

What we carry

Covers come from PPE (heavy-duty cast aluminum 9.25 front and AAM 11.5 rear covers), BD Diesel (14-9.25 front, 14-11.5 rear and a front-and-rear pack), Mag-Hytec, WCFab and the Banks Power Ram-Air cover kit. Hardware includes the PPE 138051002 rear cover gasket, the WCFab WCF100217 bolt kit and the ATS 402-009-1000 drain plug. Gear oil is here from Hot Shot's Secret, Lucas Oil and Royal Purple, in 75W-90 and 75W-140 plus 80W-90, 80W-110 and 85W-140.

Fitment notes

Count the cover bolts (the 11.5 uses 14) and check ring-gear size before you order a cover, gears, shafts or seals. The Mag-Hytec AA 14-10.5 is listed for 2003-2006 2500s with the AAM 10.5, and the AFE 46-70032 is a Dana 80 cover, so buy either only after confirming your axle. Front covers fit 4x4 trucks only. These trucks were sold as Dodge Ram and are filed under RAM here. For a 2007, confirm the 5.9L engine rather than the 6.7L before ordering. Verify by VIN.

Frequently asked questions

How do I tell which rear axle I have?

Count the cover bolts and check the ring-gear size. The AAM 11.5 uses a 14-bolt cover and an 11.50-inch ring gear. Do this before you order covers, gears, shafts or seals, because rear parts are split by axle.

How often should I change differential fluid?

Under severe service, the maintenance schedule calls for a change every 15,000 miles. For normal use, follow your owner's manual. Use 75W-90 GL-5 synthetic up front and 75W-90 or 75W-140 synthetic in the rear.

Can I keep my factory differential cover?

Yes. The 11.5 rear cover seals with a reusable rubber gasket, so you can pull it, drain, clean and reinstall at 43-62 ft-lb. If the gasket is torn, the PPE 138051002 replaces it. Go aftermarket when you want added fluid capacity for towing.

Not sure what fits? Call the shop at the number in the header, or use the fitment checker on any product page. We install everything we sell.