Hi all.
I am in the market for replacement fenders and quarters for my 70 chevelle. I really have my heart set on NOS sheetmetal. But I have been burned before purchasing parts that were misrepresented. Can anyone tell me how to tell the difference between repo fenders/quarters from NOS fenders/quarters? I am wary about trusting the "GM" sticker alone. Anything can be copied nowadays. Are NOS sheetmetal electrocoated black like repos? Thanks for all the help.
Scott

The repros are black primered just like NOS.
To spot a NOS quarter look in the rain gutter up where the trunk hinge would be. NOS 1/4's have the GM stamped into them.
9815404 for the left
9815405 for the right

As for the fenders they are tricky, but can be spotted. The spot welds on the repro's are smaller in dia, roughy 3/16. Were several OE fenders that i have are 1/4 or more.

Also the two welded nuts on the inside of the fender where the inner fender bolt too, those nuts are NOT the same. The two nuts on the repro are a tad smaller and rounder in shape.
The OE nuts are bigger in size and SQUARE .

But you know if I really wanted too, I could very easily stamp my own part numbers and weld on some different nuts. :(
As always buyer beware...Eric

I have been told that width of the wheelwell lip is also an indicator of NOS vs repo. The repo's sheetmetal there are wider than their NOS counterparts.
I checked my DRIVERS side "NOS" quarter today, has no GM part number stamped on it, and the "GM" sticker states 9815405, which is part# for the PASS side according to you. I hope this is not a fake.
How close can a "licensed by GM" reproduction panel resemble a real NOS panel?
Thanks again for the help.

Perhaps a primer in basic terminology is in order...

NOS= New, Old Stock. That means it is was originally produced by the "factory" and was the same part that would/could have been purchased from a Chevy/GM parts department and will display a GM part number. It might actually be several years old, but has never been used.. i.e. New, Old Stock.

Repro=Usually, but not always means that the part has been manufactured under license(certified) from GM/Chevrolet. It will almost NEVER have the original GM part number affixed or stamped into the metal.

Aftermarket=Copies produced by uncertified manufacturers, usually off-shore, and any number affixed or stamped on it bears no relationship to the original or a certified repro.

FWIW, GM part numbers almost always(there are exceptions) use the last number for a left side part as an odd number. Right side parts have an even number.

Not all reproduction steel is the same. Steel panels made in the US, such as Dynacorn, GoodMark etc... are of high quality steel, precise stamping and accurate measuerments. Some off shore products are equally as good (rarely) while other's are just horrible. I have seen some Genuine GM panels that are worse than the cheapest Taiwan stuff. Note; some off shore products are indeed certified by GM as replacement parts and are of generally good quality. Certification means that the die stamping, measurements, material thickness meet GM spec's. Small details like the width of a fender lip or a flanged end on a panel are all relative. Human's (not machines) do the final triming and checks so take it from there.

While tolerances and spec's are tighter today than they were 30 years ago, there is still a lot of variation in the parts. I have done a bit of collision in my trade and you would be surprised! Just keep in mind that a domestic vehicle produced 30 years ago had quite a lot of give in the tolerances and quite often (98% of the time) things were not as "tight" as one thought. They were mostly assembled by people and not machines....

Sorry if I got carried away, Hope it Helps though...