Offset shackles

I am going to go out on a limb here and say that Dr diff's kit is 1/2" front and rear, or whatever is needed to keep the leaf springs at the correct angle. I also got a measurement from him for center to center distance on the new spring pads i got as well as they needed to be moved inward.

72bluNblu are the rear leaf springs tapered at all front to rear, or are they square with everything? Mine look to be square as i have the same 1" clearance from the spring to the tire front and rear of the tire.