Quick Answer

Frequent Question 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.

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 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.

What did 12 bolt rear ends come in?

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.

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.

What’s better 10 bolt or 12 bolt rear end?

First, the 10-bolt’s pinion shaft diameter is 1.438 (25 splines) while the 12-bolt is 1.625 (30 splines) which makes the 12-bolt 13 percent larger in diameter and therefore stronger.

What rear end came in a 57 Chevy?

Automatic 57 cars (both 6 and V8) came with 14inch tires and 3:36 rear gears. Stick shift 57 cars came with 14 inch tires and 3:55 gears.

How do I identify my GM rear axle?

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.

What is the strongest rear end?

Dana 60 Rear End Assemblies

If you want a big brute of a rear end under your car, look no further than a Dana 60. Even in the heyday of muscle cars, Dana 60 rear differentials were renowned for their strength, along with their difficulty to locate.

Is Posi the same as limited slip?

Registered. Posi and limited slip are both the same thing. Standard rear end “Peg leg”, both back wheels always propel the car but the power goes to the wheel that spins the fastest. So if one side spins out, all the power goes to that wheel..

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 can I tell what rear end is in my Chevy truck?

You can typically find your RPO code on driver side door panel or glove box. General Motors rear end differentials are referred to by the diameter of the ring gear, i.e. 7.5 inch, 8.5 inch, 10.5 inch.

How much horsepower can a 8.2 10 bolt handle?

Roughly 550 to 600 HP total. No slicks, drag radials. No problems with the 8.2 at all. I used the stock diff., the Auburn would be better.

How do I know what Chevy differential I have?

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 year s10 has 8.5 rear end?

According to Chevy High Performance, the 7.5-inch was standard until 1993, when the previously optional 7.625-inch became standard. 1995 and newer S-trucks equipped with the high-output V6 were equipped with the 8.5-inch rear end.

Are all Chevy 10 bolts the same?

Nothing could be further from the truth. The 10-bolt can handle just about anything you throw at it, as long as you use the right axle, either the 8.5- or 8.6-inch. That is the great caveat
there are four sizes of 10-bolt GM rear ends: 7.5/7.625-, 8.2-, 8.5-, and 8.6-inch.

Is a 10-bolt rear end posi?

Ten-bolt rears came in both Positraction and non-Positraction versions. Although it would be much cheaper to find one with Positraction already, many aftermarket suppliers can sell you carriers, axles and gears to convert a stock non-limited-slip axle to a Positraction.

How do I know my Chevy ring gear size?

The ring gear diameter is measured across the face of the gear. To obtain the ring gear diameter, simply place a tape measurer across the gear. This can be tricky if the ring gear &amp
carrier are still in the housing. In some cases, a differential can be identified by the number of cover bolts is has.

How wide is a 1970 Nova rear end?


Year Classic Vehicles Width Rear
68-72 Nova 60″
78 & up Monte Carlo, Regal, etc. with 10 bolt axle 58″
68-72 Chevelle with 10 bolt axle
89 Trans AM (Disc brake)

What rear end came in a 55 Chevy?

Most all 1955 Chevy 1/2 ton pickups came with a 3.90 rear end ratio.

How wide is a 57 Chevy rearend?

How wide is a 55 Chevy?

Length : 195.6 in | 4968 mm.
Width : 73.0 in | 1854 mm.
Height : 59.0 in | 1499 mm.
Wheelbase : 115.0 in | 2921 mm.

What is the gear ratio on a 1957 Chevy Bel Air?

3.36 is the most common in 57s, other ratios that are available stock housing include 3.08, 3.55, 3.70, 4.11,and 4.56 etc.

How do I find my Chevy axle ratio by VIN?

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. Divide the number of teeth on the ring gear by the number of teeth on the pinion gear.

How do I know what 14 bolt I have?

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.

What is a GM 14 bolt rear axle?

The General Motors Corporate 14 bolt is a heavy duty, full floating rear axle used in 1973 to 2001 Chevrolet and GMC pickups. It is not to be confused with the smaller, semi floating 14 bolt axle, which uses a 9.5″ ring gear and is built for 3/4 ton applications.

Is a Dana 70 better than a Dana 60?

The torque rating for a stock Dana 70 axle shaft is 8966 ft/lbs, which is almost 50% stronger than the stock Dana 60 axle shaft, which has a rating of 6044 ft/lbs.

How much horsepower can a 9 inch rear end handle?

“They’re good only to 400hp max,” says Tom at Tom’s Differentials. “Anything above that should use today’s beefed-up, redesigned, nodular-iron aftermarket cases. They’re good to 800 hp, if built properly.

Is a Dana 44 good?

At the same time, the Dana 44 is a great axle if you don’t need giant tires or big power. Most people don’t realize how heavy a Dana 60 is and how much unsprung weight affects handling. The Dana 44 is also a heavy axle, but it’s significantly lighter than a Dana 60.