Not to sound completely stupid....but....what exactly is the purpose of the upper bar? I know the lower bar positions the axle housing to the body, but the upper just runs from one side of the frame to the other. What does it do?

 

sounds like it just a brace for the frame and for the panhard bar to mount to...

 

ill take a shot at this...the panhard bar is there to keep your body and rear end with you. without it, when you go aorund a corner the rear end is gonna wnat to go striaght. by attaching it to the body like they do, it keeps it stable and under the without alot of body roll. thats waht i think the upper bar is for actualy, the body roll. even though we have soild rear axles's (not IRS), that bar is there for precautoin under hard cornering? (all of this is what I THINK...not what i know )