When changing tires over to my GMC yesterday (the 04 chevy caps had them too)I saw black caps on the end of the 4 posts that hold the cap off the wheel.


These cap/plugs pull out by hand and give the extra threads needed to put them on the H2 rims w/o cutting the posts off.


This pic may show it clearer


http://www.dieselplace.com/forum/uploads/543_cap.jpg