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PML Differential Cover for GM 8½" and 8 5/8" Ring Gear, 10 Bolt, Horizontal Fins Design

Part Number 10815

PML makes two differential covers for the GM 8½, 8 5/8 inch 10 bolt rear end. See both PML GM 8½" rear differential covers to compare.

Differential Cover, GM 8.5 10 bolt Differential Cover, GM 8.5 10 bolt Differential Cover, GM 8.5 10 bolt, polished

As-cast finish
$165.00

8mm-1.25x21 bolts: Go To Cart

8mm-1.25x16 bolts: Go To Cart

5/16in-18x7/8 bolts: Go To Cart

5/16in-18x5/8 bolts: Go To Cart

Black powder coating
$220.00

8mm-1.25x21 bolts: Go To Cart

8mm-1.25x16 bolts: Go To Cart

5/16in-18x7/8 bolts: Go To Cart

5/16in-18x5/8 bolts: Go To Cart

Polished finish
$295.00

8mm-1.25x21 bolts: Go To Cart

8mm-1.25x16 bolts: Go To Cart

5/16in-18x7/8 bolts: Go To Cart

5/16in-18x5/8 bolts: Go To Cart

Click on the button under the bolt size you need to order the differential cover. Scroll down for more information on bolts.

General Information

Volume: 0.5 qt. over stock

Dimensions: See this pdf file, a separate window or tab will open

Applications for a PML GM 10 Bolt Differential Cover

This PML differential cover fits the rear end differential on many GM, GMC, and Chevrolet vehicles. Be aware that for each model and year there may be more than one rear axle possible. See also GM 10 bolt 7.5, GM 14 bolt 9.5, and GM 12 bolt 9.5.

Typical applications for this differential include the following:

½ Ton Trucks, 1979 to Current:

  • C10 & K10
  • C1500 & K1500
  • Silverado 1500
  • Sierra 1500

¾ Ton Trucks, 1979 to 1998:

  • C20 & K20
  • C2500 & K2500

½ Ton Vans, 1979 to Current:

  • Vandura
  • Express
  • Savana
  • G1500

¾ Ton Vans, 1979 to Current:

  • Vandura
  • Express
  • Savana
  • G2500

Full Size Blazer, 1977 to 1994

GMC Jimmy, 1977 to 1991

Escalade, Tahoe, Yukon,
1992 to Current (check panhard bar clearance)

Avalanche 1500

Suburban 1500, 1982 to Current

Hummer H3

Configurations vary. Always check your vehicle to verify differential and clearance.

GM 8.2 10 Bolt: These rear end covers can also fit on older vehicles with the GM 8.2 differential. For example:

  • 1966 Impala
  • 1960s Chevelle
  • 1966 Pontiac GTO

See our GM 8.2 web page for more information.

GM 8.2 with PML cover
PML GM 8.5 cover and stock GM 8.2 cover

4WD Front Applications: See PML Part Number 6077 for GM Front 10 bolt 8 1/2" ring gear differential found on some 4WD Chevy and GMC SUVs and trucks. PML part number 10815 and 6082 are for the rear differentials.

Temperature Sensor Port Option

The boss on the side can optionally be machined for temperature sensor for $45 additional (call to order machining and let us know your sensor thread size).

Bolt Information

PML includes mounting bolts with all differential covers. PML provides bolts that are longer than the stock bolts since the flange on PML's cover is much thicker than stock. The bolts with the stock cover will not work.

GM has used four different bolts on these differentials so to complete your order, we need to know which bolts you have. These differentials have used both metric and standard cover bolts. The bolt length has not been consistent either. When ordering one of these covers, you will need to pull one of your stock bolts out (a top bolt is best) and measure the length and determine whether it is metric or standard.

  • Bolt length is measured from the underside of the head (where a washer would sit) to the tip. If the bolts are metric, the length will be 21mm or 16mm. If the bolt is standard, the length will be 5/8 inch or 7/8 inch.
    Standard bolt, 1 inch long    Metric bolt, 30mm long
    These images show how to measure the bolt length. Click on small image to view larger in a new tab or window.
  • A bolt head with lines or letters on it is typically standard. A bolt with numbers such as 5.8, 9.8, 10.9, or 12.9 is likely to be metric.
  • Metric bolts will have 20 threads per inch. Standard ones will have 18 threads per inch. Since the bolts do not have a full inch of threads, try counting the number in a half an inch and multiply by two.

We know this is a hassle, but we do not want to send the wrong bolts or charge everyone a lot of extra money to cover sending all possible bolts with each cover. Watch the video for more informations on checking your bolts.

Gasket Information for a PML GM 10 Bolt Differential Cover

PML machines the gasket surface of our differential covers completely flat. The flange surface of the differential housing is also machined flat. A thin bead of RTV silicon sealant makes an excellent seal between two machined surfaces. If you prefer to use a gasket, we have had customers recommend the Fel-Pro RDS 55028-1 gasket.

PML Differential Cover Compared to Stock

PML Differential Cover Part Number 10815 height compared to stock  PML Differential Cover Part Number 10815, compared to stock
Click on image to view larger.

These images show this PML differential cover compared to the stock cover.

This image compares the depth of both PML GM 10 bolt differential covers and the stock cover. Click on image to view larger in a new tab or window.
PML GM 10 bolt Differential Covers depth comparisons

Installations

Our thanks to everyone who choose this PML rear axle cover for their truck or SUV and emailed us pictures.

2011 Cadillac Escalade EXT

Michael installed a polish finish PML differential cover on his Escalade. He put 3 coats of clear coat on it and jb welded a filter magnet to the inside which has 25lbs of holding strength. (Note that we at PML do not think the magnet is needed or necessarily a good idea since a magnet attached incorrectly could cause a lot of problems.) Michael removed some fin material since he had about 1/4" clearance and wanted to be safe if the rubber bushings flexed. Our thanks to Michael for all his feedback and pictures.
Escalade that has a PML differential cover    PML GM 10 bolt rear end cover on an Escalade    PML GM 10 bolt rear end cover with  magnet

2012 Chevy Avalanche 1500

David has a 2012 Chevrolet Avalanche 1500 which he uses to tow a travel trailer. He had to replace the bearings in the differential so he wanted to find a better way to drain and replace the fluid to avoid having to replace the bearings again. So he purchased a cast finish PML cover and powder coated it a shiny black.

David had a thermal camera and took thermal images of the stock cover and the PML cover. He took both images after towing a trailer for about an hour on a highway followed by 15 minutes of slower, steady driving. Ambient temperatures were 80F and 70F. David emailed us saying:

"I assumed that the stock differential and axle had plenty of heat-dissipating area, since the oil can flow all the way down both axle tubes.  A few square inches of aluminum fins would not add much.  The thermal images revealed a different story.  The stock differential temperature was mostly 170-200 degrees F while the PML differential was mostly 140-150 degrees F.

Our thanks to David for sharing his thermal images and comments with us. The images are below:

Thermal image of stock differential cover tmperatures on an Avalanche Thermal image of stock differential cover temperatures, from a 2012 Avalanche    Thermal image of PML differential cover tmperatures on an Avalanche Thermal image of PML differential cover temperatures, from a 2012 Avalanche    PML differential cover installed on a 2012 Avalanche 1500 PML differential cover, custom powder coated shiny black, on a 2012 Avalanche 1500
David installed the PML cover with AMSOIL Severe Gear 75W90, a paper gasket and medium loc-tite on the bolts.
Click on image to view larger.

2003 Chevy Avalanche Z71

Derek installed this PML differential cover on his 2003 Chevy Avalanche. The cover fit nicely behind the pan hard and sway bars. His Avalanche had the 8mm-1.25x21mm stock bolts.

2003 Avalanche Z71   Installing a PML cover on a 2003 Avalanche Z71   PML rear axle cover installed on a 2003 Avalanche Z71
Click on image to view larger.

2003 Chevy Avalanche Z71 4WD

Alvin measured and determined this PML cover would fit with pan hard and sway bars and decided on the cast finish. He loves his new PML differential cover.

2003 Avalanche 2003 Avalanche   2003 Avalanche stock cover 2003 Avalanche stock differential cover and clearance to sway and pan hard bars   2003 Avalanche PML differential cover 2003 Avalanche with PML differential cover installed   2003 Avalanche, PML cover, pan hard and sway bars 2003 Avalanche with PML differential cover, clears pan hard and sway bars
Click on image to view larger in a new tab or window.

2010 Silverado 1500

Torrance Transmissions in California at 310-378-9217 installed this PML differential cover on a 2010 Chevy Silverado 1500 4x4.

2010 Chevy Silverado     PML differential cover installed on a 2010 Chevy Silverado   PML differential cover installed on a 2010 Chevy Silverado, close up view
Click on an image to view larger in a new window or tab.

PML Yourcovers.com GM 10 bolt Differential Cover on a Silverado

2007 Silverado 1500

PML differential cover installed on a Chevrolet Silverado 1500. Ed selected the black powder coat finish for his differential cover. Click on image to view larger.

2014 Chevy Tahoe 5.3L

Georgio installed this PML rear differential cover on his 2014 Tahoe and his 2010 Silverado. His stock bolts were 8mm-1.25x21mm. He also installed a deep PML 6L80 transmission pan on his Tahoe. Our thanks to Georgio for choosing PML covers and pans.

2014 Tahoe with PML GM 10 bolt rear end cover    PML GM 10 bolt rear end cover on Chevy Tahoe, ground up view    PML GM 10 bolt rear end cover on Chevy Tahoe
Click on image to view larger.

2008 Chevy Tahoe 5.3L

Ian installed this cover on his 2008 Chevy Tahoe 5.3 Maggie TSV1900 supercharged at 12 lbs.

He also installed a PML transmission pan. See PML 4L65E deep pan for info on that pan and installation.

2008 Tahoe has space for PML GM 10 bolt rear end cover   2008 Tahoe with PML GM 10 bolt rear end cover   2008 Tahoe
Click on image to view larger in a new tab or window.

Note that a 2008 Tahoe Police Pursuit Vehicle (PPV) did not have the same clearance. The pan hard bar on the PPV model hit the fins on the PML cover.

2010 Chevy Suburban 1500 4x4 Z71

The images below are of Mark & Tahoe's 2010 Z71 Suburban. Our thanks to them for emailing us the pictures. They also commented on the cover: "Fit perfect! Thank you very much!!!"

PML Yourcovers.com GM 10 bolt Differential Cover on a 2010 Suburban    Stock differential cover on a 2010 Suburban    PML rear differential cover on a 2010 Suburban
From left to right: 2010 Suburban, Stock Cover, PML Cover Installed
Click on image to view larger.

PML Yourcovers.com GM 10 bolt Differential Cover on a Yukon

2005 GMC Yukon

PML differential cover installed on a 2005 GMC Yukon SLE. The finish on this differential cover is black powder coat.

Our thanks to Scott for sending us the picture. Click on image to view larger.

2006 Hummer H3

PML drilled and tapped the cover for a 1/8 NPT. The aftermarket gage and sensor installed in the cover lets this H3 owner track his fluid temperatures while on the road.

2006 H3 with PML cover PML 10 bolt differential cover on 2006 H3   Temperature sensor in PML cover Temperature sending unit installed in PML differential cover on a 2006 Hummer H3
Click on image to view larger in a new tab or window.

For a larger picture, please click one of the above images. A separate window will open showing a bigger picture. (The larger pictures take a minute to display.)

PML Differential Cover Features:

  • Increased oil capacity for cooler temperatures
  • Sand-cast aluminum with raised fins
  • 3/16-inch thick wall construction to add strength to differential housing
  • 3/8-inch thick gasket flange will not bend when bolts are tightened
  • Machined gasket surface for a secure seal using RTV or factory reusable gasket
  • Oil changes without removing the cover
  • All hardware provided, including magnetic drain plug

Learn more about finishes and construction of PML parts.