Originally Posted by XDR
I have a few of these I need to replace. Auto parts store has wrong threading. They are for the fender to firewall mounts.
They are metric 8mm x 1.25 thread pitch. It's very common to confuse them with 5/16-18 which will thread in a couple of turns and then lock up.
The correct name for them is extruded U-nut. Extruded because the part where the threads are is formed into a tube or extruded and then threaded.
McMaster Carr has them- McMaster-Carr
Watch the panel thickness, I don't believe you need them for metal any thicker than .080-.100 or so.