You can still get the heavily leaded paints shipped in from South American countries, basic marine salt water paint they use there.
Volare77.... I never noticed any difference in the replacement fenders vs the originals.
If you look at the original 76 /77 fenders they have a smooth inner lip all the way around the wheel well, the vast majority of recall fenders have the, three I think, small bumps with holes where the edge of the newer style full coverage plastic wheel well attached. The early F-s just used a small insert at the rear of the fender in front of the door hinges. And of course all use the thick tar paper push tab flap on the inside if the front inner lip which would be on the backside if where the fender brightwork trim goes, but many who replace the fenders fail to realize there should be anything there or that the fenders are set up for the full inner liners.
This makes it hard to restore a 76 properly because the 76 drivers fender is unique to that year only.
As Bud W mentioned and posted, everything rusts. The pic of his hinge is a good example imo of a different grade metal and all got poor prep and poor paint because what was the life expectancy, service life of cars in the mid 70-s. Look at the meager warranty many cars got.
But back to the fenders, the 76/77 being foolishly open everything got sprayed every time it was wet, clean water salt water, mud. I recall driving down wet gravel roads and thinking I was in a metal can being pelted by rocks.
Luckly I live in a semi arid desert with under 10% humidity most of the time, cars kept indoors dont sun rot or rust. Which is another big factor like in Bud W-s pic of the hinge, that dont happen here. Ive had block and cranks on wooden shelves for over 15 years and all they do is get dusty but never rust.
Again luckly for me, along with never putting over 50 miles a year on any one of my older mopars they never rust and the frames probably look better then they did new off the lot, but thats just a geographical benefit, no hidden methods or pixie dust.
You can see in the pic here the pathetic early F inner liner vs the 78 up and the ones used, or what should of been used with the recall fenders.
Some also got the tiny lower plastic shield and if you look in the 77 parts book 12-100 12-2 12-3 they monkey around even on the splash shields on a couple dates before and after 9/76.
I love them, but what marble heads designed our cars?
Most think they were used later m-s and such but look at the older 368 part number prefix, go look at a org. 78 F or go look at your recall fenders.
NOS 1982-1989 Gran Fury Fifth Avenue Diplomat RF Fender Splash Shield 3868968 dp | eBay