Full-fledged upgraded axle swaps are a great idea in theory, but in practice they aren't always feasible. The problem often comes down to cost: you can easily spend several thousand dollars on a new set of fully upgraded and assembled axles. While they might be perfectly configured for your vehicle and your use, they'll cost as much as family vacation to see the Mouse down in Florida.
Fortunately, you don't have to spend a truckload of cash to make some substantial upgrades to the stock axles on your pickup or SUV.
The main problem with a stock axle is that it was made for normal use, with a normal set of wheels and tires. Once you upgrade wheels and tires and start going off-road, it's only a matter of time before you deal with some sort of axle related problem:
A lot of vehicle owners solve these problems with a complete axle upgrade: pull your Dana 35 off (or whatever axle you have), and put a brand new Dana 44 in its place, complete with upgraded gears, axle shafts, and locking differential.
While that's a good solution, it's pricey. If it's not currently in the budget, there are some smaller upgrades that can make a difference without breaking the bank.
While a set of hardened axles shafts will set you back several hundred dollars, they go a long ways towards preventing problems on the trail. Depending on the type of steel you buy in your upgraded axles shafts, you can increase axle strength 50-100%. Bends and fractures are much, much less likely after your upgrade.
Axle truss systems range in price and complexity, but all of them have the same basic purpose: increase the strength of the housing via reinforcing members.
This truss from Artec Industries is a good example of what you get when you install an axle truss - additional reinforcement that prevents bending. Image courtesy Artec Industries.
While they require some welding skills to install, they're fairly inexpensive. Some companies offer decent truss kits for as little as a hundred dollars, and nearly every popular off-road vehicle has a truss kit available.
While replacing the ring and pinion is never fun or easy, it does offer you the chance to replace your OEM ring and pinion with something a bit more heavy duty. If you have the right tools (or can borrow them), it's a good upgrade.
Not to mention, you can upgrade your gear ratio in the process, allowing you to better pair the axle ratio with your wheel and tire setup.
While a lot of differential covers are showy, some of them offer more than just shine. Look for a cover that promises to increase housing strength as well as dissipate heat. The reinforced cover will help with the housing's twisting strength, while heat dissipation will keep your gear oil from cooking in extreme situations. Covers that come with a drain plug are nice too, and most of them won't set you back much more than $200.
A reinforced differential cover has some overall axle strength benefits, but also helps with cooling by increasing the fluid capacity of the differential.
Upgrading your axle is a great way to make your vehicle more reliable on the trail, and for that reason a full axle upgrade probably belongs on your vehicle modification list at some point. At least if you're building a true trail warrior.
But if you're on a budget - or if you're just looking for an easy way to make your vehicle a little more rugged without spending serious cash - this is a great list of upgrades. For the most part, none of these upgrades impact the performance of the vehicle overall, and none of them conflict with other modifications (like a suspension upgrade from Baja Kits). All of them have varying degrees of utility, with the axle shafts being perhaps the best suggestion on our list.