13 MM socket wrench and driver (for removing the old cover) 1/4 allen bit with a 3/8 ratchet drive (1/4 allen key is furnished)

6 MM allen bit with a 3/8 ratchet drive (6 MM allen key is furnished) 5/16 allen bit with a 3/8 ratchet drive

3/8 drive torque wrench Gasket scraper

Smooth flat file by 8 to 12 in. long

Oil drain pan (minimum 8 Qt. capacity)

New gear lube API Spec. GL-5, MT-1 ("LE" 607 for severe service and extreme HD applications and temperatures of -20 to 230 deg. F). ("LE 9920 75w-140 Synthetic" for warranty reasons and extreme low and high temperatures of -50 to 280 deg. F). The Lubrizol Friction Modifier bottled by Torco Co. (for "limited slip" differentials only) 4 oz. per 3 qt’s. of gear oil.  The "LE" Gear Oil and the Friction Modifier can be purchased at Mag-Hytec.



Number                      Quantity        Item



Mag-Hytec Differential cover with O-ring ARP 568-277 (installed)



8 MM x 30 MM stainless allen cap screws (Torque 12-16 ft. lbs)



5/16 stainless AN washers



Drain plug assembly with magnet and O-ring ARP 568-910 (installed)



Dipstick assembly with magnet and O-ring ARP 568-910 (installed)



Oil level reference plug with  O-ring ARP 586-904 (installed)



1/8 pipe plug (for optional temperature sender not included)



Dipstick,  Drain plug,  Reference plug  and 1/8 pipe plug (Torque to 30  in. lbs)


A word of caution to the installer / vehicle owner:


The Mag-Hytec cover is designed to fit the factory GM axles as supplied as original equipment. However, in some applications, or because of the use of certain factory options and/or after market equipment, there may be clearance problems between your Mag-Hytec cover and other vehicle systems (specifically some rear sway bars). It may be necessary to install spacers or shims to lower the sway bar. It is the responsibility of the vehicle owner/cover installer to ensure that no other vehicle component comes in contact with the Mag-Hytec cover. Contact with any vehicle component, or the making of any modification to the Mag-Hytec cover, automatically voids the warranty. Mag-Hytec assumes no liability, expressed or implied, for damage or injury to persons or property.


SEE Notice:  #15. Installation  on  Vent plug, hose and assembly



Note: For some installations, removing the spare tire may provide better access to the work area. However, it is not necessary in every case. The installer should determine if there is adequate work space prior to starting the installation.

  1. Park your vehicle on level ground and apply the parking brake.
  2. Position a drain pan under the differential to catch the old gear lube.
  3. Remove the 14 existing bolts, starting at the bottom.
  4. Using a gasket scraper, start at the bottom of the cover and carefully (so as not to gouge the housing metal) insert between the existing cover and gear housing and pry the old cover off.
  5. Allow all of the old gear lube to drain.
  6. Using a gasket scraper, carefully remove all of the old gasket material (dried silicone) from the housing.
  7. Use clean lint free rags to wipe down the remaining oil from inside the housing and to clean the housing gasket surface. The surface must be clean and flat for the Mag-Hytec’s O-ring to seal.
  8. Before installing the new Mag-Hytec cover, check the gasket matting surface on the differential housing for dents, irregularities, or gouges. Should any exist, carefully remove the high spots using a smooth flat file. BE CAREFUL NOT TO “ROUND OFF” THE FLAT GASKET SURFACE.
  9. Using gear lube, apply a thin layer of oil to the Mag-Hytec cover O-ring.
  10. Position the cover by aligning the bolt holes and start one of the new stainless steel allen cap screws and stainless steel washers at the top bolt hole and continue around the bolt pattern until all 14 bolts and washers are installed “finger tight.”
  11. Using a 6 MM hex bit and 3/8 drive torque wrench, torque the stainless allen cap screws to (12-16 ft. lbs.) in a “cross tight” pattern.
  12. Check the drain plug, oil reference plug, and 1/8 pipe plug for tightness. If you are going to install a temperature sender, do so at this time. Remove the 1/8 pipe plug and install the sender in its place. Be Sure To Use LPS All Purpose Anti-Seize or equal On The Sender's Pipe Threads. "TIGHTEN" all three: DRAIN PLUG, OIL REFERENCE PLUG and 1/8 PIPE PLUG TO (30 in. lbs) DO NOT OVER TIGHTEN.
  13. Remove the dipstick assembly and add in the new gear lube. Your new cover will take approximately 5 qt’s. to fill (bottom of axle) for the GM 14-9.5. There are two marks on your dipstick. The bottom mark  represents the minimum fill line and the top mark is the maximum fill line. YOUR OIL LEVEL SHOULD BE BETWEEN THESE LINES. Note: when checking the oil level, remember to thread the dipstick assembly in by hand until it is snug against the O-ring.  Remove the dipstick assembly and check the level.  If the oil level is at the full line, apply a thin film of oil to the dipstick assembly O-ring and reinstall. Tighten snugly to (30 in. lbs). DO NOT OVER TIGHTEN THE ASSEMBLY. Drive at least 25 miles and check oil level. If you have a special application vehicle, or your vehicle has been modified or “lifted” and the axle has been rotated, you will have to establish the correct oil level for your vehicle as the dipstick marks as supplied by Mag-Hytec will not apply. The high oil level is the top line on the Dipstick (The bottom of  the axle). The low oil level is the bottom line on the dipstick (the bottom inside of the axle tube). Once you have established the correct level, scribe a reference line on your dipstick for future reference and fill the differential.


  1. If you have a “limited slip ”differential, be sure to add the appropriate amount of friction modifier. We have had excellent results with the Lubrizol Friction Modifier product sold under many private labels can be purchased at GM or Mag-Hytec and it is compatible with the "LE" and Amsoil gear lubes. One 4 oz. bottle per 3 qt’s. of gear oil  (TWO 4 OZ. CONTAINERS SHOULD PROVIDE THE DESIRED RESULTS).


The Mag-Hytec cover is constructed of high quality aircraft aluminum and has a powder-coated finish. The bolts and washers are stainless steel.  These components require no maintenance.

From time to time you may wish to check the oil level and monitor the wear in your differential. With the Mag- Hytec cover, this can easily be accomplished by removing the dipstick assembly using a 1/4 allen wrench. You will probably notice some “fuzzy” metallic particles on the magnetic end of the dipstick. This is normal wear. Wipe the dipstick clean and reinstall by hand until it bottoms out on the O-ring. Remove the dipstick and check the oil level. If the level is between the high and low marks on the dipstick, apply a thin film of oil on the dipstick assembly O-ring and reinstall the assembly snugly. (30 in. lbs)  DO NOT OVER TIGHTEN.

We suggest you follow the manufacturer’s recommendations for the gear lube drain intervals. You may change your gear lube without removing the Mag-Hytec cover. Park your vehicle on level ground with the parking brake applied. Position a drain pan under the drain plug located at the bottom of the pan and remove the drain plug assembly. You may notice “fuzzy” metallic particles on the magnetic drain plug. This is normal wear. (If you notice any larger chips of metal on the magnetic portion of the plug, further inspection should be performed. We suggest that this inspection be performed by a professional mechanic who specializes in drive train components.) Remember to clean the drain plug assembly prior to reinstallation. Apply a thin layer of oil to the drain plug O- ring and reinstall. (30 in. lbs)  DO NOT OVER TIGHTEN.  Follow the procedure for filling the differential.

Should it become necessary to remove your Mag-Hytec cover for any reason, the Mag-Hytec cover O-ring may be  reused.    DO  NOT  USE  ANYTHING  TO  “PRY”  THE  COVER  FROM  THE  DIFFERENTIAL

HOUSING. THIS WILL DAMAGE THE O-RING. If you have damaged the O-ring, you may obtain a replacement by calling 818-786-8325. If you need to reinstall the cover and no O-ring is available, you may run a bead of RTV silicone or use a gasket on the Mag-Hytec’s matting surface face and reinstall the cover in the conventional manner.

During your vehicle’s use, you may come in contact with water above the axle seals or above the axle breather. You should inspect your gear lubricant at the earliest opportunity. Do so by following the oil level check procedure. If water is detected, follow the drain procedure and refill your differential following the  fill  procedure.


GM Install #1 - Vent Hose Assembly Modification 

GM Install #2 - 1/4 in. Pipe Vent Hose fitting install

The GM 14-10.5 rear end has a problem. When the carrier bearings run in oil it throws the oil up into the vent tube hole and in many cases will push the oil out and make a big mess on the under side of the truck. The GM fixes are #1 try to run a longer hose up as high as possible and some times that will help. The Max oil capacity for this is 4 qt’s. of gear oil and that is the bottom line on the dipstick which is the bottom inside of the axle tube.

The GM #2 way is to drill and tap for a 1/4 in. pipe hose fitting in the axle tube between the spring and the pumpkin and install a barbed fitting for a 5/16 hose. Plug the old vent tube with a plastic cap (supplied). This works very well some folks may want to use a mechanic to drill and tap for the 1/4 pipe hose fitting. With this install it takes 5 qt’s. of oil and will take the oil up close to the top line on the dipstick which is the bottom of the axle. We recommend the #2 install.


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