You are trying to give the term diagonal track bar a whole new meaning. When a long panhard bar is used, it is attached to the frame on one side of the car and to the axle on the other side of the car. The bar should be horizontal when viewed from the rear. When you jack the car up, the bar will drop down at an angle(diagonal). On a race car they may have one end of the bar adjusted up higher and it will be at an angle(diagonal).
The longer the bar, the better. There is less movement of the axle left and right. The problem with the longer bar is that everything gets in the way.
[img]
http://upload.wikimedia.org/wikipedia/en/thumb/0/0b/Panhard_rod.jpg/200px-Panhard_rod.jpg[/img]In this drawing you can see that hitting a bump, the bar would be bent by hitting the differential. If it were moved rearward toward you the viewer, it might hit the spare tire or gas tank. The mounting bracket on the axle would also have to be made stronger and heavier.
On your setup, if the bar went from the axle on the left, straight across to the frame on the right, the differential would be in the way. The first bump and the bar would be bent in a "U". Going forward is a compromise for clearance and it probably saved fabricating and installing an extra frame bracket.
Short panhard bars are used when you don't expect to have a lot of wheel travel and when trying to avoid obstacles such as shocks, sway bars, mufflers, tail pipes, gas tanks and anything else in the way.
Long bars are usually behind the axle and look crappy from the rear.
Call the guy you bought it from. He probably feels he is giving you a better product and it may very well be that he is.
