Level One: NOS
NOS (which stands for New Old Stock) is a brand new part that was made for the car when the car was made and would have been installed at the factory. It is a part that is brand new in a box and never installed on any car.
What does all of this mean and how can I tell the difference?
Levels of Parts
Level Two: Original Used
GM used is an original GM part that was made when the car was made and installed on a car and used for some period of time. I don't care if it was 30 days or 30 years, it was installed and used on a car, it is no longer NOS, so it is used.
Level Three: GM Reproduction
This is a part that was made by GM at one point in time. Then stopped making that part, but due to popular demand (or the vision that GM can make money on it again), GM used the original molds (dyes, patterns, whatever) to re-make the part again. It is not exactly the same because materials are different and so is the mass production process, but at least it is being made from GM and is close to what the original part looked like.
Level Four: Reproduction
This is a part that is in demand out there that a third party now makes. GM didn't want to make the part, GM didn't want to release the dye for the part, so some third party is making the part to be as close as they can to GM without being "exactly" like GM.... so that way they don't have to pay fees to GM or get sued for copyright infringement.
Level Five: Aftermarket
Basically this is a part that can be used on your car, but most of the time it doesn't fit the same way or even look remotely close to an original part. This would be things like Auto-Meter gauges, Holley carbs or intakes, the new 17x9 snowflake rims or something along those lines.
Experience
I have had the chance to have over 100+ second generation Trans Ams over the last 16 years that ranged from 2,000 original miles with all original parts even down to the date coded spark plug wires to 200,000 original miles with just about no original parts left on the car. I have had a chance to examine original parts next to reproductions for many of the parts on the cars.
I could go on and on about which parts are good and which parts are bad out there on the market, but please feel free to send me an email if you have any questions about anything listed here.
Here is the quick and easy answer.....
I always get questions about people looking to buy parts and sellers using terms like "NOS" and "Original". Sellers try to confuse you with terms like this in order to get more money for their product. Sometimes they just don't know what the terms means, sometimes they misuse it to get top dollar for a low dollar part. So what does it all mean? Basically, I view this as kinda like the 5 levels of parts as seen on the left.
So, is anything out there "like" GM NOS. No, nothing is GM NOS except GM NOS, that is why NOS parts sell for alot of money. Now, are the parts out there that are close.... yes. There are alot of parts out there that I bet 99.9% of the people would not be able to tell the difference if I held up an NOS part and the reproduction part. But there is still very small differences in anything that is re-made.
Alot of people throw around these terms like "NOS", and "GM Original" too loosely in the ads and auctions. Here is an example.... Since we are talking about them, some sellers will state in their listing for spoiler welting "Exact NEW OEM Reproduction Body Bead Welting".... as we all know, the welting that is out there in NOT "exact".. not at all. I could also take some photos of the original next to the reproduction and show you it is not exact. But again, people throw out these terms to try and sell parts.
Know the difference just by looking....
As long as we are on the subject, here are just a few things to point out as long as I have the photos handy. Here is a quick thing to point out.... between the NOS and GM Reproductions, here some examples to look for to help determine which is which.
GM NOS
Here is a GM NOS (New Old Stock) nose emblem that is new in the box. This nose emblem was made at the same time your car was produced. It has been around and sitting on a shelf somewhere and has never been installed on any vehicle.
GM Reproduction
Here is a GM Reproduction nose emblem that was made by GM probably around the mid to late 80's or even 90's. Then they stopped making that part, but due to popular demand, GM used the original molds to re-make the part again. It is not exactly the same because materials are different and so is the mass production process, but at least it is being made from GM and is close to what the original part looked like.
Nose Emblem Front
Here are photos of an original GM NOS nose emblem and a reproduction nose emblem side by side. Can you tell which is which? Probably not and most people out there would not be able to tell the difference either. The only way that you can tell is by flipping the part over.
Nose Emblem Back
The GM NOS has an original GM part number on the back and the reproduction does not. But when this part is installed on the car, you will not be able to tell.
Aftermarket/Reproduction fails.
Then we have the reproduction parts out there that are really just not even close to the original. Here is an example of a reproduction sail panel emblem (right) next to a GM Original (left). Here you can easily tell the difference which is which. The aftermarket barely has the same shape as the original and the colors are off and so is the general make up of the item. So there are some good parts out there that are reproduction, but then there are also the bad.
