We offer a complete line of rear end parts for the GM 8.875" commonly referred to as the 12 Bolt truck differential, this differential was utalized GM used this very popular differential in there full size Chevrolet trucks starting in 1964 to 1982.

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Having a problem with GM 12 bolt rear end?  We offer a complete line of rear end parts for the GM 8.875" commonly referred to as the 12 Bolt truck differential, this differential was utalized GM used this very popular differential in there full size Chevrolet trucks starting in 1964 to 1982. Our inventory includes ring gear and pinion sets, including aftermarket and OE gear sets. We are able to supply axles, bearing overhaul kits, carriers, cases, spider and side gears.

The Positraction units we offer include Lockright, no-Slip Powertrax, Auburn, Eaton Posi, Detroit Lockers and TrueTrac . We are a Dana Spice volume distributor and offer a complete line or ring gear and pinions to the large Dana 80 differential. In addition to the Dana Spicer line we quality offer differential products.

Specifications are provided below to assist you in the identification and setup as well as torque spec's for your Chevy or GM 8.875" differential.

 

GM 8.875" 12 Bolt Applications 1/2 & 3/4 ton trucks

Model Year
G20, G25 64-82
G10, G15 64-81
K10, K15, C10, C15

64-82

What differential ratio do you have?

Need information on how to setup ring and pinion backlash

Purchase your parts @ drivetrain.com and receive telephone access to experienced differential technician to assist you with installation, we help you solve the problem. motivegear_ligduty_large.jpg

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12 Bolt Truck Specifications

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11-1/2"
12 HOLES
Irregular Gasket Pattern


  • RG Diameter 8.875"
  • 12 3/8" X 24 RH Threaded Bolts
  • PINION Diameter 1.438", 30 Spline

    CASE: 2.56 -2.73, 2.76-3.42 & 3.73 Numerically Higher

    8620 Material Heat-Treated

    Assembly Specifications:

  • Cover Bolt Ft. Lbs. 20
  • Pinion Brg. Preload In. Lbs 24-25
  • Pinion Brg. Preload In. Lbs 10-15 Used
  • Ring Gear Backlash .005-.009
  • Ring Gear Bolt to case Ft. Lbs. 90
  • Side Brg. Caps Ft. Lbs. 60

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Chevrolet GM 8.875" 12 Bolt Truck Ring and Pinion Products

 

 

 

 

GM 8.875" 12 Bolt Differential Ring Gear and Pinion Set

Quaility Gears provide guaranteed performance

 

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Order our high performance synthetic oil and friction additive combo kit at time of order for ring and pinion or bearing overhaul kit and pay only $49.95 plus S&H, a $54.00 value. See other Red Line Oil Products that we recommend.

 

Part Number OE Number

Ratio

Teeth

Price

GM12-308  

3.08

40-13

GM12-342  

3.42

41-12

GM12-373  

3.73

41-11

GM12-373X*  

3.73

41-11

GM12-411  

4.11

39-9

GM12-411X*  

4.11

37-9

GM12-456  

4.56

41-9

*Fits 2.76 go 3.42 Case

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GM 8.875" 12 Bolt Differential Parts

   
Description

Part Number

 
Case, Empty Open 8.875" 3.73 -UP

6258086

 
Case, Empty Open 8.875" 3.42 -Down

6258088

 
Bearing/Overhaul Kit 8.875" Rear

DTSR12RMK

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Internal Kit 8.875" 30 spline Open (spider/side gears, cross shaft thrust washer)

GM12BI

Axle 30 Spline, 65-69 30 3/4" long 6 holes R&L

PA6068

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Installation Tool, Your Cost $49.98 + S&H

Axle 30 Spline, 65-69, 6 hole to 5 hole conversion L&R. 30 3/4" length.

PA5855

 
Axle 30 Spline 4wd 70-81 31 9/32" length 6 hole

PA5383

 
Axle 30 Spline 2wd 70-81 31 5/16" length 5 hole

PA5569

 

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GM 8.875" 12 Bolt Differential Positraction Units

 



Whats the difference in Positractions?
Differentials whats the Difference
Description

Part Number

Auburn Limited Slip Positraction 30 Spline

542032

Auburn Limited Slip Positraction 30 Spline

542034

Detroit Locker 30 Spline

187C150A

Eaton Large Hub GM GM Truck 1961-1980, 30 spline, 3.42 & down

19587-010

Recommended replacement for non-repairable non-working GM stock Gov-loc positraciton
Eaton Large Hub GM Truck 1961, to 1980 30 spline, 3.73 & up

19556-10

TrueTrack  30 splines  913A315
LockRight 1/2 Ton Pickup 30 Spline

1910

 
no-Slip  Powertrax 30 spline

92-0788-3005