I don't think the DTS kit is a accurate picture of what is inside the spicer 8 3/4 differential .
With the mancini kit make sure there are 2 thinner plates of the ones with the ears , some kits had the wrong plates with them all being the same size which would turn the unit into a spool basically. If it does not have them you can reuse them from your current diff, the thin plate should be the one closest to the ends the axles slides in and since they are keyed to the housing only one side will show any wear , make sure there aren't any high spots and just flip it over .