question about installing shackles

so I just got a set of belltech shackles to install on the rear end of my XJ

I have noticed that the width of the shackle is a bit bigger then the busing on the leaf spring. Im assuming I want it to be pretty tight

should I put a couple grade 8 washers on each side of the busing inside the shackle?

???

should be 2.5" inside iirc

these shackles have a ID of 2.9 guess they are too big

I will call the place I got them from