After buying some aftermarket repro sheetmetal parts, I always notice how much thinner and lighter it is than the original 60's stuff. Think about what the Chevelle, Camaro, etc., racers back in the day could've done with it or what Stock and SS racers are probably doing now. Who needs alum or fiberglass front ends or acid dipping when you can take maybe 100 lb off the front of a car with repro parts. It's all available. Thinner bumpers, radiator support, fenders, hood, inner fenders, and now even door shells. Replacement windshields are thinner too. I just bought a repro radiator support and was amazed at how much lighter it is than the original. I measured the thickness of the metal on both and the main portion (above the load carrying bottom) is .036 steel for the repro and .050 on the original. I plan to weigh them when I get the old one out. Of course there are some cars that time and oxidation has lightened considerably. Even "swiss-cheesed" some frames.

Repro lightweights :D