I’m trying to repair this frame rail around the sway bar attachment point . Trying to get an idea of the shape of the original nut plate that is spotted in. 
looks like a box shaped nut plate with maybe 3 sides ? The metal was rough on the outside rail , someone had did a bad patch job . Looks like about 3 spot welds on the bottom of the rail . Maybe the box had a front side that was spotted to the frame rail /engine side ? 

This is the only pic I can find of the replacement box I had to make, your description is spot on. I drilled a few holes in the side rail so when I bent it back up I could plug weld it in place.

 

only photo i could find.  these are OE rails.  if you stare really hard you'll get a sense of what the reinforcement looked like when new.

Thanks guys . I’m bending up a piece now that I will plug weld from the bottom and inside the rail ( outside wall) , and eventually will attach it to the inside wall with plug welds. I’ll post pics as I go along . I pulled out the nutplate and there wasn’t much to it or left of it . It came out too easy .