9.5"-12 Bolt Heavy-Duty Cast Aluminum Rear Differential Cover (Raw)

Features:

• A356.0-T6 heat-treated cast aluminum
• Raw cast aluminum finish
• Adds 0.57 quart of fluid capacity
• Half-inch external cooling fins
• Internal windage scrapers reduce churning and heat
• Cross-bracing structure improves rigidity
• Cast-in gussets add flange support
• 304 stainless plugs with neodymium magnets
• Viton O-rings on service plugs
• Fill plug set at factory fluid level
• Made for 3.0L Duramax Silverado and Sierra 1500
• For 9.5"-12 bolt axles, build code SU8

Keep Your Duramax 1500's Rear Gears Cooler When The Trailer Is Hooked Up

If your Duramax 1500 spends its summers pulling a camper or a loaded trailer, the rear differential is working harder than most owners ever stop to think about. PPE points out that excessive heat degrades the protective qualities of the differential fluid, which speeds up wear on the gears and bearings. In a limited slip differential, that constant heat can also break down the clutch packs and friction modifiers, which costs you efficiency and traction. This cover goes after the problem from several angles, starting with an extra 0.57 quart of fluid capacity that gives the system more thermal capacity. Half inch external fins help pull heat out of the cover, and PPE says they lower the differential fluid temperature. Inside, precisely placed scrapers keep the fluid from churning more than it needs to, which cuts down on heat, aeration, and power loss. The plug magnets capture ferrous particles, and the fill plug sits at the factory level so service stays simple. For a diesel 1500 that tows and hauls, it is a smart upgrade for a part that rarely gets the attention it deserves.

A356 Cast Aluminum Cover Where The Fins And Scrapers Work As One Structure

The PPE 138051400 is a raw finish, heavy duty cast aluminum rear differential cover for Silverado and Sierra 1500 trucks with the 3.0L turbo diesel Duramax. PPE casts it from A356.0-T6 heat treated aluminum in permanent steel molds, which it says gives a smooth, consistent finish and high dimensional accuracy. The cover adds 0.57 quart of fluid capacity, and half inch external fins improve heat dissipation, lower the differential fluid temperature, and add impact resistance. Precisely placed internal windage scrapers prevent excessive churning, which PPE says reduces heat generation, fluid aeration, and power loss. The fins and scrapers work together as a cross bracing structure, and cast in gussets add support to the differential housing flange for extra rigidity. The service plugs are 304 stainless steel with high temperature neodymium magnets and Viton O rings, and the fill plug sits at the factory level. PPE lists the GM OE reference as 85586188, which replaces 23243722 and 84553988. The cover is for AAM 9.5 inch, 12 bolt axles with build code SU8 only, and PPE directs trucks with the SU7 axle to part 138051200.

Fitment: 2020, 2021, 2022, 2023, 2024, 2025, 2026 GM Silverado/Sierra 1500 3.0L I6 Turbo Diesel Duramax, AAM 9.5"-12 bolt rear axle, build code SU8 only

Notes:

• For 3.0L Duramax Silverado and Sierra 1500 trucks with the AAM 9.5"-12 bolt rear axle and build code SU8 only, confirm your axle build code before ordering
• Not compatible with AAM 9.5" rear axles with build code SU7, PPE directs SU7 trucks to part 138051200
• Raw finish, a black version is sold under part number 138051420
• Adds 0.57 quart of fluid capacity over the stock cover
• GM OE reference 85586188, which replaces 23243722 and 84553988
• Fill plug is positioned at the factory fluid level, both plugs are 304 stainless steel with neodymium magnets and Viton O-rings
• Heat, wear, and fluid temperature benefits are manufacturer statements, results will vary
  

Install Instructions