To cure my bottoming out problem (with weight in the back), I bought the Timbrens for the rear. I installed them and I'm just a little worried that I didnt install them correctly. The instructions that came with the Timbrens say do not use the included spacer for the Nissan Xterra, so I didnt. My truck is an 06 4x4 S Model, stock, no lift. Question is, the Timbrens fit in there perfectly, slight space between the bottom of them and the axle, slight, is this correct?