I picked up a set of Chevy westcoasters for my 3500 got tired of the lousy small mirrors. The set comes with rivet nuts to attach the mirrors to the doors. I'm asking the best way to install the nuts, do I need to purchase a rivet gun or can I drill the holes install the nut and slowly tighten up the mounting bolt into the nut? The size of the nut is M8 x 1.25 mm x 20.4mm the hole I'll drill is 13.5 mm . Would just slowly tighting do the job? I don't want to goof this up. Any help would be greatly appreciated.