Which 14-Bolt Rear Axle Does My Three-Quarter Ton Suburban Have?

First Find Out If It’s a Light-Duty, New Style, or Old Style 14-Bolt Axle

Off-roaders like the full-floating 10.5 GM “Corporate” rear end. That’s because they’re inexpensive, super tough and easy to source from a junkyard. Enthusiasts and builders buy these to swap into their Jeeps or trucks. They’re also commonly found on Suburbans from the mid-1970s to today in various iterations.

The GMC or Chevy Suburban is a great all-around utility vehicle. It’s designed to haul trailers, pack gear and has plenty of room to transport the whole family. Finding out which 14-bolt rear axle combination your Suburban has can be a challenge. Read on and you’ll be able to determine which axle you have and the right one to purchase if you wish to upgrade.

14-Bolt Corporate Axle

Some enthusiasts get confused about GM’s “Corporate” moniker on some components such as rear ends. Here’s the story on that. In the 1960s, GM’s divisions all designed engines and parts for their cars independent of each other. They worked in silos. Rarely did two brands share each others’ parts. By 1973, they decided it was more cost-effective to use the same components across all of their brands instead of separate rear ends for each.

The heavy-duty 14-bolt “Corporate” rear axle came about because of the new all-for-one mandate at GM. The early axles were full-floating designs. They had a 10.5-inch ring gear and a pinion with a pilot bearing mounted at the end. The pinion bolts onto the front of the housing. This is an important distinction because it is an excellent way to tell which rear end you have. Look to see if the pinion has a flange behind it that bolts to the housing. If it does then you know you have the 10.5 14-bolt axle.

There’s also a 9.5 14-bolt axle that is a semi-floating design. It’s a better upgrade over some other GM axles like the 10-bolt or 12-bolt. But, the axles are the same size with only a larger ring and pinion and axle shafts. These rear ends are offered with both 6-lug and 8-lug wheels. They also have larger diameter axles with 30-splines on them.

10-Bolt Axle and 12-Bolt Axle Rear Ends

Our reference to the number of bolts is for how many there are on the differential cover. If you have the 10-bolt or 12-bolt style differential cover, it’s not a heavy-duty axle. Off-road enthusiasts and builders swap these for the larger, full-floating 10.5 differentials with 14-bolt covers.

14-Bolt 9.5-inch Rear End

14-bolt full float rear axle Suburban14-bolt semi float rear axle Suburban

GM’s 14-bolt 9.5-inch ring gear rear differential can sometimes be confused with the 10.5-inch (ring gear) Corporate axle. The 9.5 is a semi-floating design that uses C-clips. These clips retain the axles inside the differential housing. The heavy-duty 10.5 axle shafts bolt in with 8 bolts at the wheel hubs.

The 9.5-inch axle is easily differentiated from the 10.5-inch by looking at the hub. If it protrudes through the center of the wheel, it’s the more desirable 10.5-inch full-floating rear axle. While the 9.5-inch gear is generally a durable axle, it’s less desirable for high torque applications. Suburbans and pickups with 6- and 8-lugs use this 33-spline axle with a C-clip. It was in production through 2009.

Swapping Axles

As noted earlier, the 14-bolt full-floating axle is a more desired axle for off-road and heavy-duty use. If you’re pushing big horsepower and torque, towing or off-roading, the full-float is popular for many applications from Jeeps to big pickup trucks and SUVs like the Suburban or Silverado. But to make sure everything fits, you need to measure the width from hub to hub. Even if the gear set of the donor axle is not ideal for your use, having the correct width is the crucial factor in choosing an axle.

The early design 14-bolt full-floating axles used from 1973 until 2000 had drum brakes held on at the wheel studs. These are sometimes called stud mounted drums. These axles have a smaller pinion pilot bearing. The later versions starting in 1988 have a larger pinion bearing. You can remove drums without taking out the hub and axle shaft.

Disc Brake Kits for 14-Bolt Axles

One of the most significant upgrades that Suburban owners and 14-bolt axle users make is swapping the old drum brakes for more modern disc brakes. The single-wheel 14-bolt disc brake conversion kits bolt right on. While you can use the information we’ve outlined here for identifying your rear axle type, it is recommended that you remove a wheel to verify the full floating axle. You can’t rely on looking up the vehicle by make, model, and year, especially on older trucks and Suburbans, because you don’t know what the previous owner(s) may have modified. You’ll have to do some sleuthing, but in the end, it will be worth it to get the correct axle and disc brake kit.

When it comes to brake parts and disc brake conversion kits for three-quarter-ton and 1-ton trucks and SUVs, Lugnut4x4 is your one-stop. We have everything you need to repair your brakes and to make those conversions as easy as possible. Contact us today with any questions you have about the heavy-duty brake parts you need.