Ok, once again I searched and couldn't find anything. I'm looking for the thread size of the nut that attaches the front bumper through the fender. I'm not near the car so unfortunately I can't look at it, but I seem to recall there just being a stud towards the top of the bumper cover. I hope I'm remembering correctly. It's for a Firebird.

 

I believe it's an M6 x 1. Has an attached washer.

 

So it definitely wasn't M6. Might not even really be threaded? Either that or my stud is in really bad shape. Here is a pic of what I'm asking about. Sorry about the bad picture:

 

It is a threaded stud, I don't know if I've ever seen what the factory originally had there, no car I've worked on had the original hardware there. The original fitting was probably some sort of speed nut or push retainer. I'll go measure the support bar I have and see what size it is.

 

Checked it out, not really threaded, but I think it is a push type retainer. This is an 89 formula. It us about m6 size so you. Ight be able to crank a nut on it.
Here's a pic.
I think this is what fits it:
http://www.clipsandfasteners.com/M6_...c_p/a14980.htm

 

Did anyone ever figure out what size the self threading nuts are? I picked up some M6 and they are definitely to small.

 

Its an automotive speed nut.
I have no idea what size it is. I just bought a package of assorted sizes from the local car parts store and some of them fitted. they cut their own thread

 

Should be a 10mm (speednut).