Well, you could contact some of the prominent junkyards and salvage dealers in your area. A simpler option would be to go online and check out some online vendors like autopartsfair, mkauto and mypartshop, I am sure you will find the parts you are looking for at these sites. In fact the first dealer in the list, autopartsfair has more than 35 million spares which have OEM certification and come with a warranty.

Sources: http://www.autopartsfair.com/usedcarparts/

The federal government-sponsored "Cash for Clunkers" program about 2 years ago brought in a HUGE selection of 1960's-1970's-1980's-era vehicles to junkyards all over the nation. One local junkyard even had a 1956 4 door hardtop Chevy ! Rather then touring the nation, you can consult http://car-part.com, which is a website used EXCLUSIVELY by US and Canadian junkyards for selling parts. You find your listing, give them a call (they are usually not very e-mail literate, it always ends up in no response when I've emailed), get shipping prices, and proceed. You can pay by credit card, and have the part shipped to you. A little over a year ago, I got a 1966 chevy truck steering column complete (I wanted a harder-to-find floor-shift configuration, not three-on-the-tree) in Colorado, shipped to California, total cost about $85. With the price of parking, the price of admission, and the price of hot dogs at most car swap meets, combined with the rather limited geographical coverage of those attending as sellers, this is a good way to begin your search. It not might prove 100% fruitful, but it's one way to look, even while you are in bed !