Rear Axles (weakest to strongest)
27. Dana 25
It has several weak points when overtired and overpowered, including the axletubes, differential gears, and two-piece axleshafts.
26. Dana 35
It has a very weak and flexible housing that causes C-clip axle and differential problems. Unfortunately, it has unbelievable aftermarket support despite its weakness. However, consider any upgrades to this axle a Band-Aid for the real problem. If you're running it hard (especially with a locker) and it hasn't spit out its insides and it's not bleeding gear oil out of the pressed-in tubes and plug welds, it soon will be.
25. Low-pinion Dana 30(Mexico CJ)
It's a rare pile, but it's out there. It has weak tubes, a smallish ring gear, and two-piece axleshafts.
24. AMC 20 (CJ)
The AMC 20 is marginal in a stock application. It has a very weak and flexible housing that can lead to other problems. The two-piece axleshafts are notoriously fail-prone. Much like the Dana 35, this axle is best swapped out if you are planning to spend money on it or run larger-than-stock tires.
23. Chevy 10-bolt
Much like the Dana 35, it has a very weak and flexible housing that can lead to other problems. An abused Gov-loc is a death warrant for the 10-bolt rearend. It's not a swap-worthy, full-width axle for Jeeps.
22. '06-and-earlier Wrangler Dana 44
The smallish axletubes (same as Dana 35) can flex and cause carrier bearing and other failures if abused. It has lots of aftermarket support but limited available ratios if you are using the stock Rubicon differential.
21. GM 12-bolt
Similar to the GM 10-bolt. It has a flexible housing and weak tubes for a full-width axle. It's not really a good 4x4 axle worth swapping into a Jeep.
20. Toyota 8-inch
Overall, it's a stout axle for its compact size. It actually makes an OK Jeep swap, but is often frowned upon for being an import part. The Toyota 8-inch has lots of aftermarket support.
19. Alum Dana 44 (ZJ)
It's a decent, relatively durable axle, but there isn't much aftermarket support because it's fairly uncommon.
18. Chrysler 8.25
It's a decent axle when mated with moderate-sized tires, however, few gear ratios are available. It doesn't have much aftermarket support.
17. Ford 8.8 (Ranger and Explorer)
Some versions have weaker 28-spline shafts. The '91-'01 Explorer 31-spline version is preferred ('95-and-later have disc brakes). There's a lot of aftermarket support for the 8.8, but the C-clip shafts are a notable weakness. Commonly swapped into Wranglers in place of the Dana 35, although the marginal gain in strength hardly seems worth the effort.
16. Toyota Land Cruiser
They're getting harder to find, but they're still usable for a Jeep in need of an offset rearend, albeit an expensive oddball possibility with C-clips. An offset Dana 44 from a Quadra-Trac FSJ would be a better option.
15. Ford 8.8 (fullsize version)
All have 31-spline shafts and undesirable C-clips retaining the axles. Not a particularly good full-width axle for a Jeep swap.
14. Dana 44 (non-Wrangler)
Much like the Dana 44 front axle, the 44 rearend enjoys a lot of aftermarket support in the form of optional ratios, floater kits, and aftermarket differentials for more traction. Some early models are plagued with small bend-prone axletubes, weak coarse-spline shafts (as well as two-piece shafts), and coarse-spline pinions. Early '70-and-later Dana 44 rears are much more desirable. Look for 2 3/4-inch axletubes and 30-spline, one-piece shafts.
13. AMC 20 (FSJ)
The FSJ AMC 20 is stronger than the CJ version and perhaps about equal to the strength of a newer Dana 44. However, it doesn't enjoy as much aftermarket support as the Dana. Fewer gear ratios and lockers are available.
12. '07-and-later Wrangler (Rubicon only) Dana 44
It features stronger tubes than the axles in the previous model Wrangler and 32-spline shafts. It's sure to see plenty of aftermarket support, including complete assemblies available from Mopar.
11. Chrysler 9.25
It's only found in Dodge trucks and vans. Even though it's relatively strong, it's not all that great of a swap for a full-width axle. Very few ratios and aftermarket differentials are available for the 9.25. It's also a C-clip axle.
10. Ford 9-inch
It's the king of aftermarket components. The 9-inch came in Ford cars and trucks and can be found in many configurations, lug patterns, and widths; junkyard versions are becoming more difficult to find. Look for the stronger 31-spline versions over the weaker 28-spline. Most axles can be converted to stronger 31-, 33-, 35-, and even 40-spline shafts with bolt-on parts. Plenty of differentials are available and gear ratios ranging from 2.80:1 to 6.50:1 are easy to find. Complete aftermarket housings and entire assemblies are available.
9. Full-floating, 30-spline Dana 60
These are extremely common and can be easily found in junkyards under Dodges, Fords, GMs, and Jeeps alike. They are most often found under 3/4-ton vans and pickups, but a few came under Mopar musclecars. There is a lot of aftermarket support for the Dana 60.
8. Semifloating Dana 60
It's a little rare, but it can be found under early F-150s and early-'70s FSJ pickups. It features desirable 35-spline shafts and uses common Dana 60 gears and carriers, so a lot of aftermarket ratios and differentials are available.
7. Full-floating Ford 10.25
The ring gear is huge, but aftermarket support is not. The gear ratios and differential selection is limited. Heavy use will also cause the axletubes to break free and rotate inside the centersection. Not a great full-width swap.
6. Full-floating 35-spline Dana 60
They enjoy plenty of aftermarket support because they use common Dana 60 gears and carriers. However, they're very uncommon, and you're not likely to find one in a wrecking yard. Many 35-spline 60 rear axles have been converted from 30-spline housings.
5. Rockwell 2 1/2-ton
Rockwell rear axles are often two to three times less expensive than their frontend counterparts. The housing, gears, carrier, and bearings are extremely durable. The 16-spline axleshafts are not. Aftermarket shafts are available to bring it above Dana 80 strength. Only one gear ratio and few lockers are available. Due to size, 6.72:1 gearing, and weight, it's not a good axle for tires less than 44 inches tall.
4. Full-Floating GM 14-bolt
The 14-bolt is the king of cheap beef when running tires up to and more than 44 inches tall. You can't deny the strength of the 10 1/2-inch ring gear, huge 30-spline pinion, and 1 1/2-inch, 30-spline axleshafts. It also enjoys a decent number of aftermarket gear ratios and differentials. The fact that it has a removable pinion support and spanner adjustable backlash makes 14-bolt gear and differential swaps relatively easy. It can be found in GM 3/4- and 1-ton trucks and vans in a few different widths. It's often found in wrecking yards for less than $200 because it's so common. Perhaps its only real weakness is the thin tinfoil-like diff cover.
3. Full-floating Dana 70
The Dana 70 is another member of the cheap beef squad. However, there are several versions making them more difficult to identify. Look for the Dana 70U or 70HD. These feature desirable 1 1/2-inch, 35-spline shafts. There are also plenty of ratios and a good number of aftermarket differentials available for these versions of the 70 as well. They are often found in 1-ton Dodge, Ford, and GM trucks, vans, and even some tractors and heavy equipment.
2. Full-floating Dana 80
This is the step into medium-duty truck axles. The Dana 80 is more axle than most people will ever need. There are plenty of ratios available that range from 3.31:1 to 5.38:1 and a good number of aftermarket differentials.
1. Full-floating Dana 135
The Dana 135 is found in some Ford F-550 medium-duty trucks and motorhomes. It features a removable third member like a Toyota or Ford 9-inch. However, its size is more on par with an 18-wheeler rear axle. The massive size and heavy-duty design make it undesirable for all but the biggest-tired Jeep swaps.
What is your Jeep's designation?
CJ: '46-'86
DJ: '56-and-up Postals
FC: '56-'65 Forward Control
KJ: '01-and-up Liberty
LJ: Wrangler Unlimited
MJ: '86-'92 Comanche
SJ: FSJs, or fullsize Jeeps, like Wagoneer, Gladiator, and M-715
TJ: '97-and-up Wranglers
VJ: '48-'50 Jeepster
WJ: '99-'04 Grand Cherokee
WK: '05 Grand Cherokee
XJ: '84-'01 Cherokee
YJ: '87-'96 Wrangler
ZJ: '93-'98 Grand Cherokee