The Currie RockJock 60 rearend comes with Currie’s excellent bracketry that allows track bar adjustment. Ours is loaded with Yukon 4.88 reverse-cut 60 gears and a Yukon Grizzly Locker. Currie’s new cast cover is thick, strong, and looks great. We originally used the stock JK muffler but blew it out, so we installed a MagnaFlow RV big-block muffler that’s relatively quiet. A loud muffler causes headaches at the end of a long day on the trail.