PML GM 8.5, 8.6 Rear, Vertical Fins Differential Cover

Description

Volume: 0.5 qt. over stock, approximately

Dimensions: Click here for dimensions.

Number of Bolts: 10 bolts, Guidelines for Bolt Sizes (click here), opens in new tab or window

PML makes two covers for the GM 8.5, 8.6 inch ring gear differential, 10 bolts. This cover has a classic round shape and straight vertical fins. For the other cover, see PML GM 8.5, 8.6, Horizontal Fins differential cover, which offers more clearance.

Benefits:

Extra capacity
Drain hole and magnetic drain plug to simplify maintenance
Large, vertical fins for heat dissipation
Sand cast aluminum construction for thick walls
Machined gasket flange for a secure seal
Round shape similar to profile of stock cover

Note that 8.6 is a short hand reference for the 8.625 or 8 5/8 when written as a fraction.

For a GM 8.2 10 bolt, see 8.2 Rear Differential Cover Info.

Applications

This PML cover fits the GM 8.5, 8.6 rear differential. Many GM, GMC, and Chevrolet vehicles since the 1980s have this. Be aware that for each model and year there may be more than one rear differential possible.

Configurations vary. Always check your vehicle to verify differential and clearance. Some typical vehicles that MAY be able to use this differential cover:

½ Ton Trucks, ½Vans and ¾ Vans, 1979 to Current:
- C10 & K10
- C1500 & K1500
- Silverado 1500
- Sierra 1500
- Vandura
- Express & Savana
- G1500 & G2500
¾ Ton Trucks and Vans, 1979 to 1998
- C20 & K20
- C2500 & K2500
Chevy and GM SUVs
- 1977 to 1994 Full Size Blazer
- 1977 to 1991 Jimmy
- 1982 to Current Suburban 1500 (check for panhard bar clearance)
- 1992 to Current Avalanche 1500, Escalade, Tahoe, Yukon (check for panhard bar clearance)
- Hummer H3 (check for panhard bar clearance)
2002 to 2012 Canyon and Colorado (many models have similar GM Torsen 8.0)

1960s and 70s GM Muscle Cars: some may have a GM 8.2 differential, which is very similar and was used in cars such as Chevelle, GTO, Impala, Monte Carlo and Nova. Check bolt hole pattern carefully. See 8.2 Rear Differential Cover Info.

2023, 2024 Canyon/Colorado: Contact PML for information.

Police Pursuit Vehicles: generally PPV models have less clearance.

Pan hard and sway bars: See PML GM 8.5, 8.6 Horizontal Fin differential cover, which has more clearance.

Front Differential: See PML GM Front 8.5 differential cover. This cover is for the rear.

Installations

List of Installations Pictured Below

2008 Sierra
1993 Silverado
1996 Imapala
1968 Camaro

2008 Sierra

Steve installed this cover on his 2008 Sierra 1500 SLE with a 5.3 V8 engine.

PML Cover Installed 2008 Sierra Stock Differential Cover
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1993 Chevy Silverado

Damon installed this PML 10 bolt rear differential cover on his 1993 Chevy Silverado 6.3L 383 SS truck. Both his truck and his dog are ready to go for a ride.

From left to right:
Supplies for installation, adding fluid, PML cover installed, 1993 Silverado with PML cover

Click on image to view larger.

1996 Impala SS

Installation and video by Hoagie's Garage. This Impala had oem bolts size 5/16in-18x7/8 bolts on the stock diff cover.

1996 Impala SS PML differential cover on a 1996 Impala Plenty of space behind PML rear differential cover on a 1996 Impala SS Drain on PML 10 bolt GM rear differential cover on a 1996 Impala. Magnetic drain plug included with cover.
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1968 Camaro

Hawaii Racing in Simi Valley, CA, installed this PML cover on a 1968 Camaro with a Hotchkis sway bar.

OEM cover PML differential cover
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Specifications

Optional Temperature Sensor Port

The boss on the side can optionally be machined for temperature sending unit. There is a machining charge and a plug is included.

Bolt Information

GM has used four different bolts for this differential. See Guidelines for Bolt Sizes (click here), opens in new tab or window

Gasket Information

PML recommends RTV or paper/fiber gaskets or cork composite gaskets.

PML machines the gasket surface of our differential covers 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.

Some of our customers have recommended the Fel-Pro RDS 55028-1 gasket.