Jeep Repair: Knocking Rear End Sound, jeep grand cherokee, tank trailer

Question
1998 Jeep Grand Cherokee Limited 4.0L 4x4

Starting the Vehicle I start to hear a knocking type sound coming from the Rear Passanger Side.
Going over bumps (any size,) the knocking/clunking sound appears as well.
It is getting louder but, weird part is that at times you don't hear it/doesn't appear.
Any suggestions as to the cause?
Brakes have been done recently (rotors, pads, etc by dealership) but, the sound did appear prior to that - just getting louder and louder now.

Appreciate any assistance and thank you in advance for taking the time to review the above!

Answer
Check your exhaust and make sure it's in the hangers properly.  If you've had the catalytic converter replaced then chances are high that the angle just isn't right.  Your exhaust could be hitting the gas tank, trailer hitch or suspension.  This is the ONLY thing I can think of that will make a "knocking" noise sitting still and the exhaust on the good old ZJ's exits right rear if I'm not mistaken.  Just grab hold of it (cold) and wiggle it to see if that's your noise.  If it's getting louder then your exhaust could actually be slipping out too so don't hesitate to jump on this.
Doug