GM 8½" and 8 5/8" Ring Gear, 10 Bolt
Differential Cover

P/N 10815

As-cast finish
$165.00

8mm-1.25x21 bolts:

8mm-1.25x16 bolts:

5/16in-18x7/8 bolts:

5/16in-18x5/8 bolts:

Black powder coating
$215.00

8mm-1.25x21 bolts:

8mm-1.25x16 bolts:

5/16in-18x7/8 bolts:

5/16in-18x5/8 bolts:

Polished finish
$280.00

8mm-1.25x21 bolts:

8mm-1.25x16 bolts:

5/16in-18x7/8 bolts:

5/16in-18x5/8 bolts:

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 PML GM 10 Bolt Differential Cover

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

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 & newer
(check for panhard bar)

Avalanche 1500

Suburban 1500, 1982 to 2006

Hummer H3

These rear end covers also fit on older vehicles with the GM 8 1/2" differential. For example:

• 1966 Impala GM 8 1/2" differential, 10 bolt
• 1960s Chevelle, GM 8 1/2" differential, 10 bolt
• 1966 Pontiac GTO with GM 8 1/2" differential, 10 bolt with slight bolt hole modifications (please email or call for details)

Note that these covers will not fit the front axle 10 bolt 8 1/2" ring gear differential found on some 4WD Chevy and GMC SUVs and trucks.

Temperature Sensor Port Option

The boss on the side can optionally be machined for temperature sensor for $40 additional (call to order machining and let us know your sensor thread size).

Bolt Information

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.

• Metric bolts will have 1.25 threads per mm (20 threads per inch), standard ones will have 18 threads per inch. Also, 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.
• 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.

So there are four different bolts possible with these differentials. Be sure to order the correct one for your vehicle. When you look at the ordering selections above, the last number is the length and the middle number is the threads per inch or mm. 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.

When you get your cover, it will include bolts that are longer than the stock bolts since the flange on PML's cover is much thicker than stock. Our bolts are 3/8-inch or 9mm longer than stock bolts. The bolts with the stock cover will not work.

Installations

Yukon, 2005

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.

Silverado 1500

PML differential cover installed on a Chevrolet Silverado 1500. The finish on this differential cover is black powder coat. Click on image to view larger.

Cadillac Escalade EXT, 2011

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.
     

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