there are a few ways to tell, the first is to look at the cover in the back.... if its ovalish with 10 bolts holding in on, and a rubber fill plug, you've got a 8.25... another mor involved way to tell is to either take off the cover or the wheel and brake assembly, the 8.25 uses c clips located in the spidergears to hold the axleshafts in, and thus have no bolts behind the brakes to hold the shafts in... i believe that Jeep started using the 8.25 on and off sence '92......
I do not believe they are replaceable, I believe thay are available aftermarket.
Most I believe came with a 904 Transmission. Depends for the rear. The auto came with a 2.76 rear, and the stick came with a 3.23-3.55 rear.
The 2014 Jeep Cherokee has 49.9 in. of rear hip room.
The 2014 Jeep Cherokee has 40.3 in. of rear leg room.
The 2001 Jeep Cherokee has 38 in. of rear head room.
The 2001 Jeep Cherokee has 35 in. of rear leg room.
The 2014 Jeep Cherokee has 55.1 in. of rear shoulder room.
The 2001 Jeep Cherokee has 44.3 in. of rear hip room.
The 2001 Jeep Cherokee has 54.1 in. of rear shoulder room.
The 2014 Jeep Cherokee has 38.5 in. of rear head room.
They came with a Dana 35 or Dana 30 one is the front the others the rear I forget which, but I'm thinking it's the Dana 35 for the rear.
The rear track of the 2014 Jeep Cherokee is 5 ft. 1.9 in. (61.9 in.).