Rear sway bar install

Anyone install a rear sway bar on a 71/72 that did not come with one from the factory? There are generic holes (about 1/2") in the frame but no threads to mount the ‘U’ bracket, bushings. What is needed to mount those ‘U’ brackets?

Some use a nut attached to one end to insert the “u” bolt into the frame, the bushing bracket is then attached to the threads that protrude from the frame. The bolt in the frame is the weakest part of the set-up and has been known to ‘pull through’ the frame…

Factory used a threaded plate spot welded to the bottom inside of the frame rail… only the front hole and third hole are threaded, I assume the others are for alignment when it was welded

Pic is of my 71 RH rail…
To install a plate you would need to make a hole in the trunk floor for access to drop it in.
Does your car have these holes already? If so the front and 3rd holes are where the bar mounts…
Jim