Classic cars and their auto parts are a tradition of this country. The USA is unique in its value of the personal rights of the individual citizen including the right to personal property. This means that there are a lot of collectors and just like anything else that people value cars break and need replacement parts.
Older cars are valued for their age and the history they signify. They also wear down over the years and require restoration. The problem is that there is a finite supply of these old auto parts as the models are no longer made. So there is a significant market for these parts. This is what I want to discuss in the next several paragraphs.
So auto parts are often sought to restore a car to its original working condition which is a state that is valued to relive important history. Therefore the demand is high which makes it easier to locate the auto parts because their sale can be a lucrative endeavor. So where do you find these parts and where do they come from?
Well anywhere you find antiques you can find these parts. Old estate auctions, flee markets, and antique malls. The problem is that these can be considerably time consuming and often not very productive. So before you go you should do your research. Body shops are good resources as they are constantly seeking auto parts, car collectors are another valuable source of information. Another great resource is the internet which brings together basically all people with a similar interest in the form of forums, or bulletin boards, or blogs. If there is a part you have the best chance of finding it on the internet.
Another great place to look for things like outdated auto parts is on the online auctions like ebay. If people seek it, that is if there is a market for it, than it is generally being sold on ebay. Often just like when you restore anything you may have to purchase more than just that one part (i.e. a whole car that is often in disrepair or inoperable) but that is what you deal with. The internet is also a great place to shop for parts for your new guns as well as there are liquidators and wholesalers for things like this on the web.
Hopefully this gives you a start as you seek to restore and/or repair that symbol of American freedom. Happing auto parts hunting!