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GM 9½" Ring Gear, 14 Bolt, Pattern Fins, Differential Cover

Part Number 9504

PML makes three covers for this differential. See all PML GM 9½" rear differential covers to compare.

PML GM 9½ Diff Cover, as-cast PML GM 9½ Diff Cover, black powder coat PML GM 9½ Diff Cover, polished

As-cast finish

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

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
(no fill or temp sensor boss)

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

Volume: 1.0 qt. over stock

Dimensions: Click here for dimensions.

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.

Number of Bolts

The stock cover has 14 bolts. We eliminated the bottom bolt hole to better center the drain plug. The PML cover is thick and stiff so there are not any leaks. Hundreds of customers, including PML's president, run this cover without a problem.


These PML rear end differential covers fit the 14 bolt 9½ inch rear differential on many Chevy and GMC trucks, vans and SUVs. PML offers three different covers to accomodate a variety of makes and models. Typical applications include the following.

  ½ Ton Trucks, 1988 to 2013:

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

¾ Ton Trucks, 1979 to 2004:

  • C20 & K20
  • C2500 & K2500
  • Silverado 2500 & Sierra 2500 (not HD)

¾ Ton Vans, 1981 to 2013:

  • Vandura
  • Express
  • Savana
  • G2500

1 Ton Vans, 1982 to 1995:

  • Vandura
  • Savana
  • G3500

Suburban ¾ Ton: 1988-2013

Avalanche (see 10303-2)

Hummer H2 (10303-2 only)

SSR 6 Speed (10303-2 only)

Trailblazer SS (10303-2 only)

Part number 6070 generally will work on older trucks and SUVS (pre-2000) as these vehicles have plenty of clearance behind the rear differential.

Part Number 9504 was designed for newer (late 1990s and newer) GM/Chevrolet trucks and SUVs where the spare tire, frame cross member or sway bar runs behind the rear differential.

Part Number 10303-2 is for the Hummer H2, Trailblazer SS, and SSR 6 Speed because a sway bar is right behind the cover.

Dimensions are provided for each part number so you can check your vehicle to make sure the PML cover will fit.

2014 and newer Silverado and Sierra 1500, please see our new 12 bolt rear cover.

Be aware that for each model and year there may be more than one rear axle possible. Check your stock cover shape or number of bolts.

PML makes three differential covers for the GM 9 ½ inch 14 bolt rear end. For other options, see all PML GM 9½" differential covers.

PML Differential Cover Compared to Stock

PML Differential Cover Part Number 9504 height compared to stock  PML Differential Cover Part Number 9504, 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 all PML GM 9 1/2, 14 bolt differential covers and the stock cover. Click on image to view larger in a new tab or window.
PML GM 14 bolt differential covers depth comparisons


2010 GMC 1500 Denali

Leon's Transmissions in Garden Grove, 714-534-3300, installed a black powder coated differential cover on a 2010 GMC 1500 Denali. They also installed one of our new 6L80 transmission pans on the truck.
GMC 1500 Denali with a PML differential cover, extra capacity    PML differential cover getting installed on a 1500 Denali    PML differential cover installed on a GMC 1500 Denali, tire spacing
Click on an image to view larger in a separate 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.