If you use the GM centers, you need to use the lugnuts that have the threads on the outer lip.
The black caps on the centers are what screw onto the lugnuts to hold the center cap on.
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2006 Quad 4X4 Auto White, Silencer ring MIA, intake gutted, Amsoil Nano, Magnaflow 4", Smarty Jr, Dashhawk monitoring....Tows a 2008 Wildcat 32QBBS