My clunk turned out to be a loose lower control arm bolt in the rear. Your description is exactly the same issue I had.
2002 Jeep Grand Cherokee 4.0L, 4x4, Selec-Trac TC, Auto Transmission
K&N drop-in air filter, B&M Supercooler Transmission Cooler, Rusty's Off Road Front Tow Hooks, Mopar Hitch. Iron Rock Off Road 3 inch lift.