Good catch Matt. I never thought about the rear spacer being smaller than the other lift spacers on the market. If your only talking an inch I wouldnt be to worried about needing any other parts in the rear end. Regardless, one thing I do recommend on any lifted XK that goes off road is a Rusty's Adjustable rear track bar. More and more members are finding that their rear drive shaft hits the gas tank/skid when the rear is articulated. The last thing you want to do is ruin an expensive drive shaft.