Quick Answer

Quick Answer: How do I identify a Chevy 12-bolt rear end?

The easiest way to identify a 12-bolt rearend is obviously by the 12 bolts holding the rear cover onto the axle housing. The pinion shaft on passenger-car differentials is 1-5/8-inch in diameter and the cover is oval, measuring 10-15/16-inches wide by 10-5/8-inches tall.

Are all GM 12-bolt rear ends the same?

They are not interchangeable. That doesn’t mean the truck rearend is not capable of receiving performance upgrades. To the contrary, aftermarket 30-spline differentials and axles are available. GM car and truck 12-bolt rearends are easily distinguishable by the cover shape.

How do I identify a Chevy 12-bolt?

12-bolt axles can be identified by casting numbers on the bottom of the cast-iron center-section and on the front of the passenger side axle tube. This identifies the car make and model, gear ratio, date of casting and assembly and factory of origin.

How do I identify my Chevy rear differential?

If the ID tag or stamp is missing or unreadable, differentials can be identified by the number of cover bolts, the distinctive shape of the cover, the number of ring gear bolts, and ring gear diameter.

How do I identify my GM truck rear end?

Identify your GMC or Chevrolet rear end gear ratio by the RPO Codes, usually located on the placard labeled “Service Parts Identification” inside the drivers door panel or glove box.

How do I identify my GM rear end?

Information about Differentials in GM vehicles can usually be obtained by looking at the RPO or “Regular Production Option” codes contained in the Service Parts Identification tag in the glovebox. Whenever possible, reference the tag numbers when ordering parts for your Differential.

What size is a GM 12-bolt rear end?

12-Bolts to Glory The GM 12-bolt debuted in 1965 and was mass-produced until 1972. It features an 8.875-inch ring-gear carrier held in place with two internal main caps.

Are all GM 12 bolts the same?

A different 12-bolt differential was used for light truck applications, but those 12-bolt units are not directly interchangeable. You can identify a truck differential by the smaller, 1.438-inch diameter pinion shaft and the size of the rear cover, measuring 10.875 inches by 10.875 inches.

How do you find the gear ratio on a 12-bolt?

Count the number of teeth on the pinion gear and count the number of teeth on the ring gear. Divide the ring gear teeth number by the number of teeth on the pinion. The result is your gear ratio.

How do I identify my GM differential?

Without an ID tag, differentials are identified by the number of cover bolts, the distinctive shape of the cover, the number of ring gear bolts, and ring gear diameter. They can also be identified by whether the center section is an integral or dropout design.

How do I know what rear end my s10 is?

How to Identify an S-10 Rear End

  1. Look under the rear of the vehicle. The rear end is centrally located between the rear wheels.
  2. Match the shape of the differential cover on the back of the rear end housing to the gasket shape chart found on Roadkill Customs Differential Identification page.

What VIN number is my rear end gear ratio?

The gear ratio is usually listed in the VIN code located on driver’s door, the glove box, or the ID plate on the dashboard. Count the times a rear wheel goes around for one driveshaft turn: if its 3 1/2 it’s a 3.50:1.

What rear end do I have by VIN?

Identify the VDS section, the fourth through eighth digits of the VIN. This section typically includes information such as the vehicle model, engine size and body type. While not every vehicle manufacturer includes gearbox ratio information in the VDS, this will be where the information is found if it was included.

How can you tell the difference between an 8.2 and 8.5 rear end?

Another way to tell the difference between an 8.2 and an 8.5 rearend is to pull the cover and look at the bolt holding the spider gear crosspin. If it takes a 1/2-inch wrench to remove it, it’s an 8.2. If it takes a 5/16-inch wrench to remove it, it’s an 8.5.

How many quarts is a 12 gauge bolt?

Registered. A 12 bolt should only take around 3 quarts until it comes out the fill hole.

How do I identify a GM 14 bolt rear end?

You can spot a semi-float 14-bolt axle by counting the lugs (if it’s a six lug wheel, it’s a semi-float), or by looking at the wheel surface. On a semi-float axle, the axle shaft terminates at the wheel mounting surface. So, there will not be a visible axle end. NOTE: Some semi-float axles have 8-lug nuts.

Does VIN number tell gear ratio?

If you’re wondering why we’re doubting the VIN codes capability, you might want to know how to find gear ratio by VIN. The Vehicle Descriptor Section (VDS) of the VIN will carry information for the gearbox ratio if the specific manufacturer includes it.

How can I tell what gear ratio I have without pulling cover?

With the transmission in neutral, rotate the rear driveshaft by hand. Count the number of driveshaft revolutions required for one revolution of the tire. If the driveshaft turns approximately 3-1/2 times, you have a 3.54 ratio, etc.