If you are looking at Oklahoma salvage yards, it has been awhile since I was last there but in a little town of Fairview, there was an overlooked yard that had several old GM trucks my last visit. They were very easy to deal with and very reasonable.
http://www.fairviewautosalvage.com/ There is another pretty close that is much more visited. They are on I think 3rd generation of the family running it. They have a lot of stuff but the section with the older cars and trucks, they encourage you to stay away from as they want to sell those vehicles "complete". Bud's Salvage in Aline.
https://www.facebook.com/budsok/ When I was younger, a buddy and I would take a day off of work and just have a blast running all over Bud's pulling parts and looking through their storage buildings. They had a wall of picture of cars they have brought in over the years. Good times!
