When I was younger, I read a story about the Fiero and how it was made. They built the frame on a jig with boxes on the frame filled with epoxy or something like that. Then the frame went to some machine that drilled all the body mounting holes into those boxes at the same time. When a Fiero got wrecked, all they had to do was repair/straighten the frame to factory specs, fill the boxes with epoxy and redrill the holes. It was called the space frame. Here's a good story on the history of that car...
Kill Your Darlings: The Birth and Death of the Pontiac Fiero - Ate Up With Motor
If you repaired it to the factory spec's, why would you have to re-drill the holes?
I actually owned, and repaired, my wife's '84 Fiero, after it got rear-ended by a 5 ton truck. At the time, it was only 6 months old, and there was little known about repairing one.
In 1984, most car bodies were built without precision. Generally, there was enough slop in the mounting holes, and an occasional shim used, to make things fit fairly well. However, it was not at all uncommon for the sheet metal on one side of a vehicle, to fit better than the other. Or, for one car to have better fitting sheet metal, than another.
In fact, the first thing a bodyman usually did, if he bought a new car, was spend an hour, with a wrench, and a pocket full of shims, re-aligning the doors, the fenders, the hood, and the trunk, to his satisfaction.
The Fiero was the beginning of the concept, of making everything fit precisely, right out of the box. By using a jug that ground, and drilled, all the mounting blocks for the entire vehicle at one time, they were able to fit them all the same. Any variance in the under structure, called a "space frame", was eliminated, when this jig was lowered on to it.
The "mill and drill" pads were simply epoxy blocks that acted like shims, to set the height. They were drilled, to allow metal screws to anchor the body panels into the steel body structure under them.
You did not re-fill the epoxy, during a repair. You either reused it as it was, replaced them with new, or put a shim with it, if needed. People quickly learned, trying to figure out how to "mill" the new pads to the correct height, during a repair, was impossible. So, they were generally reused.
Because the outer panels had little room for adjustment, it was no fun repairing a Fiero. They required precision, that was not available with the equipment available at the time. Few guys looked forward to working on them.
Today, all cars are built with a high degree of accuracy, and little adjustment in the outer panels. Many even have the door hinges welded on, so their is no adjustment in them at all. We have now developed the skills to deal with them, as well as better measuring equipment that simplifies repairing them.
