8 3/4 axle shaft seals

Thanks 73Duster!
My 8 3/4 never had shims in it when it was given to me. My 67 maintenance manual does not show having shims. I did not use shims when I took out my 3.55 and put my 2.76 back in. I adjusted the axle and everything seems to be fine. How critical is it to have the shim in? Thanks for the partr number.

Dave