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  • BD Differential Cover Kit Installation – AAM 11.5" (Duramax, GM, Dodge)

Installation instructions for the BD differential cover kit, part #1061825, fitting the AAM 11.5″ rear axle on 2001-2013 Duramax 2500/3500, 2001-2007 GM 8.1L gas and 2003-2014 Dodge 2500/3500 trucks. The cover adds capacity and protection for heavy towing. Check kit contents before disassembly.

Download the Original PDF Manual

IMPORTANT: Please read all instructions before installation. Please check to make sure that you have all the parts listed in this kit before you start the disassembly of your truck.

Applications

  • 2001–2013 Duramax 2500/3500 — AAM 11.5″
  • 2001–2007 GM (gas) V8-8.1 — AAM 11.5″
  • 2003–2014 Dodge 2500/3500 — AAM 11.5″

Kit Contents

  • 1601825 — Differential cover (Qty: 1)
  • 1601831 — O-ring gasket (Qty: 1)
  • 1601715 — Bolt M8-1.25 × 30mm (Qty: 14)
  • 1601512 — Washer 5/16″ (Qty: 14)
  • 1601613 — Drain plug 3/4-16 (Qty: 1)
  • 1401557 — Plug -10 ORB / fill plug (Qty: 1)
BD Differential Cover Kit contents for AAM 11.5" (Duramax, GM, Dodge) - cover, O-ring gasket, bolts, washers, drain plug and fill plug
Kit contents — BD differential cover (1601825), O-ring gasket (1601831), M8 bolts (1601715), 5/16″ washers (1601512), drain plug (1601613) and fill plug (1401557).

Fitment — Identify Your Axle

SPECIAL NOTE: In 2003 Dodge released a Standard Output Diesel with an AAM 10.5″ axle. The 1061825 cover does not fit this application. Confirm you have the AAM 11.5″ axle before installing.
Comparison of AAM 14-10.5 inch and AAM 14-11.5 inch axle ring gears - this cover fits the 11.5 inch axle only
AAM 14-10.5″ (left) versus AAM 14-11.5″ (right). This cover fits the 11.5″ axle only.

Removal

WARNING: Ensure the vehicle is secure on a hoist or using wheel chocks to prevent rolling, and apply the parking brake. Do not install this cover on ground that is not level. Ensure the differential fluid is cool before starting this removal/installation procedure. Removal of the spare tire may provide better access.
  1. Place a drain pan under the differential.
  2. Using a 1/2″ socket, remove all bolts starting at the bottom. Do not remove the top bolt.
  3. Loosen the top bolt half way — this will prevent the cover from falling once you pry the cover from the housing (ensure you do not damage the housing when scraping off the silicone gasket from the differential housing).
  4. Once the cover is free, remove the top bolt and cover, then clean the gasket surface.
Factory differential cover removed, gear oil draining from the axle housing into a drain pan
With the bottom bolts out and the top bolt loosened, pry the cover free and let the gear oil drain into the pan.

Installation

  1. Install the drain plug into the BD diff cover (8mm Allen wrench). Do not overtighten.
  2. Apply a thin layer of oil to the supplied O-ring gasket, then install it into the gasket groove on the BD diff cover. Use care not to twist or roll the O-ring when placing it into the groove to ensure a good seal.
  3. Check the differential housing gasket surface for irregularities and remove any high spots if required. The surface must be flat and clean.
  4. Using the supplied bolts and washers, fasten the BD diff cover to the housing and tighten finger tight, starting from the top (6mm Allen wrench).
  5. Once all bolts are finger tight, torque them to 24 ft-lbs in a crisscross pattern.
  6. Fill the differential with the manufacturer-specified gear oil/amount plus 0.7 L (approximate fill amount 4.3–4.9 L total) for the BD differential cover, following the manufacturer's filling procedures. Insert the fill plug (1401557); do not overtighten (9mm Allen wrench).
    NOTE: Some differentials may require special additives. Please check your owner's manual before filling.
  7. Drive at least 50 km (31 miles), then re-torque the bolts to specification and ensure there are no leaks. Installation is complete.
BD differential cover showing the location of the fill port
BD differential cover with the fill port called out. The drain plug installs on the lower face of the cover.

Torque Specifications

  • Cover bolts: 24 ft-lbs in a crisscross pattern; re-torque after driving 50 km (31 miles).
  • Drain plug: 8mm Allen wrench — snug, do not overtighten.
  • Fill plug (1401557): 9mm Allen wrench — snug, do not overtighten.
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