Help,adding the sharfin antenna for Xm

[dynoray]

ok,i have asked about this recently here and on other forums with no avail. so i went ahead on my own. 2012 2500 hd, i'm adding xm to my truck with no onstar /xm option. i need somebody to tell me what size the holes are for the sharkfin antenna. maybe somebody has a template? that would really help. just so you know i bought the GM XM upgrade kit # 20940402 it comes with the xm receiver,harness for it,shark antenna and cable for it ,as well as a bracket for the receiver and instructions.being there was no kit for the 12 i tried this one and it works flawless! even GM says its not for the truck.only shows to 2011. i have the US8 radio that would be for the XM anyway,so plug and play. figured i would share this. Just need help with the antenna mounting.thanks and i can send a couple pics of the kit. Ray