Swapping In 3/4-Ton Axles

Here's the dilemma: For most forms of off-roading, you can't beat a short wheelbase. That's why Jeeps, early Broncos, Scouts, and the like are so popular. In the fullsize spectrum, that's also why Blazers, Jimmys, Ramchargers, and 1/2-ton trucks are the rage. But with any of the fullsizes, you get a 1/2-ton running gear with tons (literally) to stress the axleshafts, gears, pinions, and driveshafts. These components have their own way of letting you know when you've asked too much.

It's no surprise that the most popular upgrade you can make to these vehicles is to swap in 3/4- or 1-ton axle assemblies. This fixes almost all the shortcomings of the lighter-duty axles, and in most cases the parts aren't that difficult to install.

The truck used for this conversion is a '76 GMC 1500 that came with a Dana 44 frontend and a 12-bolt rearend. Dana 44s were used until mid '77, when the 10-bolt frontend became 1/2-ton equipment, and 10-bolts replaced 12-bolts completely in '83. Both 3/4- and 1-ton GM trucks used 14-bolt rears, so the real difference is in the front. Through mid '77, the 3/4-ton frontend was the same Dana 44 used under 1/2-tons. The rotor and hub were different and had the eight-lug wheel pattern. The 1-ton trucks used a Dana 60 up front, which is the ultimate in strength, but these are extremely pricey pieces. If your tire size or type of wheeling demands the strongest you can find, you'll want the 60.

The 14-bolt advantage is undeniable strength while the drawbacks include cost, lost ground clearance under the pumpkin, and weight. In addition to larger pieces and a pinion that's fully supported, eight-lug 14-bolts are full-floaters. This means that the weight of the vehicle is on the hub instead of the axleshaft.

We’ve heard both ends of the spectrum regarding swapping a 1/2-ton to 3/4-ton gear: It’s more expensive and difficult than you think versus it’s an easy bolt-in. We went to Off Road Unlimited to find the truth and realized that, while it’s not a 100 percent bolt-in procedure, it’s not that intimidating either.