Why do some 1972 chevrolet impalas come factory with 1973 rear bumper

I have 2 frends who own 1972 impala custom sedan with a 1973 style rear bumper they swear the've had them since new,one proved it, and that's the bumper it came with .However other frends tell me thats impossible since the 72 had narrower lights .Who's right??

While I had a new VW Super Beetle and a new T-Bird that year I couldn't tell you the shape of the tail lights on the Bird.

Have you gone online and looked up "72 Chevy Impala Custom" either with or w/out quotes then looked at the images to see what you see.

It may be that the production date on the two cars may be separated by several months and would have allowed GM to run out of one near the beginning or near the end of the model year. This could cause the problem in tail light size/back up lights. Another possibility is that a bumper was replaced, after all, it's been 38 years and a fender bender way back when could have caused the bumper to be replaced and different rear lights added.

Not having owned a GM car until my van in '95' I'm a little ignorant about GM's after @ 1964.

I hope this helped.