VACUUM DISCONNECT FRONT AXLE DANA 30
In 1984 the first Jeep Cherokee XJ was produced. The 4x4 XJ's came standard with a Dana 30 front axle with a vacuum disconnect 4wd system. You can distinguish this unit by looking at the right side of the axle next to the knuckle and wraps around the axle tube.
This system consists of a finger or fork that engages the front axle when the transfer case is put into 4wd. This also means the right inner axle is a two piece. In my opinion stay away from these axles. They are simply a pain in the ass. It's hard to repair, harder to trouble shoot.
They make a conversion kit to eliminate the vacuum disconnect and to convert the 2 piece axle into a 1 piece.
This system was used on most all 4wd Cherokee's till around 1991. After 1991 all Dana 30's were a one-piece axle design.
DANA 35 REAR AXLE
The Dana 35 also known as the Dana 35 C "Custom" meaning the axle came unfinished from Dana.
The Dana 35 has been found in a wide array of vehicles from the Jeep Cherokee XJ, Commanche, Wrangler, Ford Explorer, and Ford Ranger.
The Dana 35, in my opinion, is a great axle and so is non-vacuum disconnect Dana 30. They will serve most Jeep XJ owners well for years with not much maintenance at all.
But if you plan on doing serious off roading I would recommend axle shaft upgrades at least in both the Dana 30 and 35
If your not sure what you have in your XJ if you have ABS (Anti Lock Brakes) you have a Dana 35. No ABS and you could have the 8.25 Chrysler or Dana 35.
DANA 44 REAR AXLE
The Dana 44 is the "The" rear axle to have in your Jeep Cherokee XJ if you do any kind of heavy towing or serious heavy duty off-roading.
The Dana 44 can be found on the XJ from 87 - 89 but not all of them usually just the XJ's with the towing package and almost every Jeep Comanche MJ.
Believe it or not the Dana 44 has been in use for all kinds of vehicles since the 1950's and has seen use in 1/4, 1/2, 3/4 and 1 TON rated trucks!
CHRYSLER 8.25 REAR AXLE
The 8.25 rear axle is the most common rear axle in the Jeep Cherokee XJ from 1987 till 2001. The consensus is that is the pre-1997 XJ's 8.25 is just a tad bit stronger than the D35.
The 1997 and up XJ's 8.25's have bigger axle shafts, a stronger housing, gears, axle tubes and carrier. All of which is a lot bigger and stronger of the D35.