[dmjlambert]

I was wondering about that myself. I had one that was rusty and busted out and beyond hope of putting back in. All I had was a square hole. By accident at the hardware store I found cage nuts. I thought they were interesting so I bought one for a few cents. it turned out to be just what I needed. I have not yet installed my door panels. Here is what one of those welded in or pressed in factory nuts looks like, and the cage nut. They are 1/4-20 thread size.