These cars are prone to rust and it can appear anywhere. I've been battling this stuff for 30 years!
I live in Toronto and have a 70 convertible that I've owned since 1977. In 1981 I replaced the rusted out front fenders with NOS fenders. I never drove the car in the winter. By 1987 the fenders developed major rust in 1) the top of the fenders around the headlight buckets and 2) the bottom of the fenders near the rockers.
So now I'm looking at replacing or repairing the fenders again! This time it going to cost alot more than the $300 I paid back in '81.
THe problem was that you used NOS parts. I was told that back in the late 60's they started using recycled metal, but they didnt have the process correct, so a lot of the metal actually had rust already embedded in it, which caused the 70's cars to rust like crazy in any unprotected spot, because it actually started from within. I was told thats also why they invented rustproofing. One thing I do know, is that I bought a 73 Cuda brand new, and by the time I sold it 8 years later, the trunk pan and floors had holes, and I only drove it during the winter 2 or 3 years out of the 8 years that I owned it.
Which brings up an interesting question. Do reproduction parts rust out as fast as the original parts did? I know they are thinner, but if the story about recycled metal is correct, then the reproduction parts should be made from better metal, which means that they should not rust from within.
