75 Dart - as thin bodied as they say?

I've been looking at buying a 75 Dart that appears solid as a rock and free of body filler. Weird, huh? Guy says he got it out of a barn 5 years ago, cleaned it up and shot it with new paint, drove it, sold it to a friend and now that friend is selling it again.

A buddy of mine heard I was looking at a 75 and adamantly warned me that the mid-70's Mopars were paper thin and liable to rust prematurely. This one apparently didn't rust out because it was stored indoors for many years. If I were to expose it to the wet marine air we have here in Maine it is apt to rust through everywhere in short order.

My initial thought is this sounds like a load of bull. But then again, I have a late 80's Chevy van that has metal on it thin enough to use for toilet paper, so I know car companies are not above shaving a few pennies where they can.

So tell me... is my friend full of sh@t? Or is he right?

These answers might very well make the difference of me buying this wicked cute little Dart.