The big difference would be where the steering box is located.
If you have cross link steering, or a rack, it wouldn't make a single bit of difference where the shackles are. But if you were to mount the shackles at the rear and have a rear mounted steering box with a drag link coming forward to your axle you would have some serious bump steer. The shackle rocking back and forth is bringing the axle back and forth with it. So if you had a drag link between the box mounted on the frame and the axle mounted on the spring that is rocking back and forth your wheels would steer without you turning the steering wheel!