2004.5-2007 Dodge 5.9L Cummins Rear Differential Covers

Rear differential covers on the 2004.5-2007 RAM 5.9L Cummins

The AAM 11.5 under the 3500 and heavier-duty 2500 configurations has an 11.50-inch ring gear, 30-spline full-floating shafts and a 14-bolt cover sealed by a reusable rubber gasket. Factory ratios were 3.42, 3.73 and 4.10. Cover bolts torque to 43-62 ft-lb. The axle holds 3.8-4.2 qt of 75W-90 or 75W-140 full synthetic, and 75W-140 is the call for heavy towing behind a 5.9L Cummins.

Why upgrade the cover

A finned or deep aluminum cover adds fluid capacity, and that extra oil is the reason towing owners make the change. Pair it with 75W-140 synthetic and the rear is set up to the heavy-towing spec. If you are only changing fluid, the factory cover and gasket can go back on; when the gasket is torn, replace it instead of reusing it.

What we carry

Pacific Performance Engineering offers heavy-duty cast aluminum AAM 11.5 14-bolt rear covers and the 138051002 rear cover gasket. Wehrli Custom Fabrication has the WCF100113 AAM 11.5 rear cover and the WCF100217 rear cover bolt kit. Mag-Hytec offers the AA 14-11.5 cover, and BD Diesel has the 1061825 14-11.5 cover plus a front-and-rear pack. Banks Power sells its Ram-Air differential cover kit, and ATS Diesel Performance supplies the 402-009-1000 drain plug for ATS covers and pans.

Fitment notes

Two covers here need extra care. The Mag-Hytec AA 14-10.5 is listed for 2003-2006 2500s with the AAM 10.5 rear, and the AFE 46-70032 is a Dana 80 cover. Order either only after you confirm your axle. Cab-and-chassis trucks use different axle and suspension specs from pickups. These trucks were sold as the Dodge Ram and are filed under RAM here. A 2007 can carry the 5.9L or the 6.7L, so key your order to the engine, and verify by VIN if unsure.

Frequently asked questions

Can I reuse the factory rear cover gasket?

Yes, if it is in good shape. The AAM 11.5 uses a reusable rubber gasket, so a clean, undamaged one can go back on at a fluid change. If it is torn, the PPE 138051002 is listed as a replacement. Aftermarket covers vary, so check what each one calls for.

What torque do the rear cover bolts take?

The spec for the AAM 11.5 cover bolts is 43-62 ft-lb. If you install an aftermarket cover, follow that maker's instructions where they differ. The WCFab WCF100217 bolt kit is an option if your old bolts are worn or you want fresh hardware.

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.