ORIGINAL: ncgrunt
There is one shim in each diff case, on one of the outdrive bearings. All you need to do is check the gear mesh after you transfer everything to the new cases. If it's not smooth, move the shim to the other side and if that doesn't fix it, remove it entirely. The shim is clearly shown on all the exploded diagrams of the diff's.
I moved the shim to the other side as stated above and it improved turning the shaft smoothly immensely. Although it is turning smoother now, there is still some binding when turning the shaft, will removing the shim completely hurt the setup in anyway?
Also since the diffs are so easy to get at, do you recommend using grease or silicone oil? and what weight oil do you recommend?