My repro's went right in with no problem. I painted them with a high quality paint/primer/sealer and undercoated the inner sides. They aren't going anywhere for at least 30 years!
With plastic or fiberglass, you have to worry about cracks or breaks and I've never seen one that fit right.
I like the fact that my truck is made of metal, that's one of the reasons I own only old cars/trucks. I say let the plastic for the newer cars where it belongs! LOL