How to Identify a Chevy Rear Endby Floyd Drake III
A rear end of a car is the combination of the rear axle and differential gears located at the rear of the vehicle encased in either a cast-iron or aluminum housing. It converts the torque sent by the transmission, enabling the power transfer that drives the vehicle. According to Chevrolet High Performance, the most common GM/Chevrolet rear ends are the 7.5- and 8.2-inch, 10- and 12-bolt and Dana 60. Although Chevrolet has used different rear end models throughout its history, all can be visually identified. Casting codes can also be used to identify the manufacture date.
Count the number of inspection cover bolts on the rear end housing. The inspection cover is on the back of the housing, seen by looking forward under the license plate at the rear of the vehicle. It is a round cover, fastened with bolts, used to gain access to the differential gears.
Identify the most common GM rear-end types. According to Year One Tech, the bolt number count is as follows: 10 bolts on GM 10-bolt, 8.25 and Dana 60 rear ends, 12 bolts on the GM 12-bolt rear end and nine bolts on the GM 7.25.
Look at the shape of the inspection cover and the gasket. All Chevrolet rear ends can be identified by comparing the gasket shape to an identification chart similar to the one found on Drivetrain's differential identification page (see References). A visual chart of different GM/Chevrolet rear ends is found on Ring & Pinion's differential types web page (see References).
Locate the GM manufactured rear-end casting date on the housing. It is located at the base of the housing, on a flat surface facing upwards. It consists of a letter and three numbers, i.e., A141. The first position, "A" represents the month of manufacture, in this case, January. The second and third positions represent the day of the month and the last position is the decade year. Month codes begin with "A" for January and end with "L" for December.
- According to Nasty Z28, the GM/Chevrolet 12-bolt rear end was manufactured from 1965 through 1971. After that, GM instituted the "Corporate" rear end, a 10-bolt rear end that integrated feartures of both the 10- and 12-bolt rear ends.
- Rear ends with measurement designations are named after the diameter of the ring gear, i.e. 7.2 and 8.5 inch.
- As Chevrolet used many different rear-end models throughout the years, casting codes vary in both location and translation. Information given is for GM-manufactured rear ends. Other rear ends are still identified visually with the information given.
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