Here are just a couple for sale sites for your interest.
KSL link will take you to Cars and classified’s mainly in the Utah and Idaho area, Utah borders Colorado and is a great place to look for cars, the misconception of cars being rusted out from salt on the road around salt lake city is not true as classic cars are not driven in the winter and are mostly garaged. Utah is a wealthy state and because of that people are always buying and upgrading cars/toys so bargins are out there to be had especially in the middle of winter (NZ summer) when american people are asking the question “why are we storing these vehicles that take up so much garage space”
Craigslist is a huge widely used site in America for trading and selling, this link will take you through to the Denver area in Colorado where you will be able to pick through the years of cars and parts and other things of interest. You are also able to search neareby citie’s to broarden your search range.
These are the two main sites I use. Craigslist is the number one site used in America for personal selling and trading, Check these sites out and see whats out there, If anything takes your eye message me with your details and questions.

