Took my rear bumper off to cut some trunk rust out and noticed there are no bone spacers in the rear bumper. The rear left had been hit before and the bumper is not original as the inside has ‘73 914 written from a junk yard.

I did not notice gap problems before. Are bones necessary and how did I not notice?

Yes, they keep the bumper properly spaced from the body, and to a certain extent, keep it from chipping the paint where it would otherwise make contact

Not a deal breaker. Probably left off because they are a pain if you do not tape them to the mounting brace. You have that tucked in bumper look.

You don't have to tape them in. Just get some M8x125 all thread and cut 4 six inch pieces off. Locktite them into the bumper, and slip the dog bones over them. It makes installing the bumper infinitely easier. You don't have to worry if the dog bone slipped, and it helps hold the bumper up on one side while you put the fender washers and nuts on the other side.

That is exactly what I did... I ordered some M8 stainless scews, washers and nuts...