As many of you have commented. Many of us have modified our cars or bought them so modified by now the tag does't mean very much. That said, an originally built 6pk or Hemi; that tag may be worth more money than the actual car. I'm sure many of you have gone to the Nationals and see cars pulled from a swamp being sold for thousands just for that tag.
My car started life as a Y2, /6 in 72. I blew it up as quickly as I could (that was not easy) in the 80s and put a 383 in it. I painted it with a GM color called Pharaoh Gold and custom stripes. It's now coming back to life as a 71, Y3, 383 Billboard, Gran Coupe, 'CUDA. A total mish-mash. No value to an original /6, so the fender tag means nothing. However, I intend to put the tag back in as that is how (what was left of the original car) was born. I was only able to save about 35% of the original car from the rust monster. Many parts came from my crushed 71 GC and 72 Cuda.