New coil overs causing problems...

[Double Venom]

Terry, think of it as a large pop rivet with internal threads in the barrel-minus the pin.
They come in different sizes, materials and configurations. For the rear arms I would suggest the same thread size as the sway bar bolts (3/8's ?) with a large flange and steel, not aluminum! Problem is it takes a special type tool like a rivet gun to install them and the steel is even harder to squeeze.
Basically you over drill the hole for the riv-nut to fit, force the rivet nut in place, screw in the threaded tip from the riv-nut gun and squeeze. This will cause the rivnut to compress in the hole, fitting very tight. Unscrew the tool and you're ready to now install the bolts!
I'm sure someone here can tell you where you can find them on the net.

I know guys, including me that have put the nuts in without the tool simply by putting 3 or 4 greased washers on a bolt and screwing them in until it starts to compress the nut-but hard to do and if the rive nut starts to turn in your fitting, give up, drill it out and try again!
DV