You are calling a panhard bar like they show in their photo, one that goes from the frame to the center of the axle. A diagonal track bar that you said you received, goes from the frame to the axle on the opposite side. Here is a web page that explains how a panhard bar reacts to left and right cornering forces and the effects of engine torque and body roll. They are talking about the longer bar and calling it a panhard. Both bars will center the axle, but the shorter bar will follow a smaller arc and allow the axle to move left and right a little more if you have a lot of suspension travel.
panhard I doubt it would make any difference on a street vehicle as far as handling. If it hangs down below the axle as opposed to the one they show, it would make a difference in what you see from the rear.
