I'm seriously considering making my own side sills very similar to these:
http://www.lotustalk.com/forums/f157/diy-side-sills-165625/ and I am looking for the very best fastener choice.
The OP thread mentions M6
rivet nuts but I'd want to be sure that these are indeed the best method of attachment (though I'm likely to use aluminum stock slightly thicker than .100").
My other concern is drilling under the sill area. Again, the OP smartly used a drill stop, but I hope he wasn't just lucky not to hit an oil line or something. Is there anything else that I should consider so I don't f---- something up?