I spent a heck of a lot of time trying to find auto parts for my classic cars. I rehab a car a year and usually the best places to find rare parts are from companies that buy junk cars. They usually have a wealth of parts stored and inventoried in their yards or they have relationships with other salvage yards and they share their lists of parts.
It’s almost a science when trying to find vintage parts for old cars you’re trying to restore. The salvage business has grown up around these large inventories of parts all around the country. I haven’t spent anytime trying to go overseas but from what I have read, Cuba has a huge demand for these parts because all of their cars are from the 40’s and 50’s; mostly all American makes and models.