Back End Noise?
 

I have a 2000 Grand Cherokee Limited with Quadra-Trac II, and 4.7 v8.
Whenever the car moves more than a few mph, the back end seems to grind, and it feels like it's dragging on the ground.
My rear differential has been leaking for a while (haven't had the money to fix it), and the ABS light came on shortly before this happened. Additionally the brake light has sporadically come on and off for months now.

rear end is probably toast because its low on fluid from leaking, takes like $40 and a ratchet to reseal a diff, unfortunately its now going to cost a whole lot more than that. ABS is probably because the rear axle is locking up and not matching front axle's speed. brake light is probably unrelated but if its been flashing on and off for a while id check the fluid level, either your pads are shot or youve got a leak. good luck

You may find this amusing, but when the ABS light bulb burns out, the BCM turns on the brake light! I had problems with my ABS unit and don't like it anyway, don't need to for inspection, so I took the bulb out. Then the "brake" light came on. I put the bulb back in and put a piece of black tape over it! LOL!

Is this a modified jeep or stock? This is the modified section.

Mark pretty much summed it up. Did you ever add fluid at any point? If not, then this unfortunately is the consequence. If you were unable or couldn't afford to fix it while it was leaking, then you're not going to be able to do it now. If for some reason you are, I would inspect the entire brake system, fix/replace what is needed and do a good bleeding with fresh fluid in addition to a new/repaired rear axle.