I'd take the rear shocks off and inspect them to see if they are still pressurized with oil in them, just removing one end would probably tell you, and spin your tires in neutral off the ground so you can check the runout.
Also give your driveshaft a good wiggle to check the u-joints and pinion bearings for slop. It would help to have it on the ground for this, but slightly rolled off the parking pin and wheel chocked so the driveshaft has some free play and isn't holding the vehicle from rolling.