When I restored the car I changed from rear mount ZF to side mount. In making the mounts I welded a nut in the bottom side of the chassis structure.
This was done because at some point I might make a custom tub. I have some ideas in mind. In the mean time I have used the studs to bolt in a plate/platform to stand on when working in the trunk.
Was looking at it the other day and thought it would be easy to also use the studs as a display to hold documentation for car shows and events. So I made up a stainless display that quickly bolts in and out: