I called Legendary just a few months ago and asked one of the guys on the customer handling end about their source of materials and they guy I spoke with seemed very knowledgeable about a lot of their products (I was calling on behalf of one of my friends in Finland who bought my 1971 Charget R/T recently and wanted some bucket seat covers that were the houndstooth variety that is the D5 code below).
His vinyl/cloth is the X9 below (body code plate says D5X9)
The guy at Legendary told me they get their material mainly from SMS so as to best match the original vinyls/cloths.
That makes me wonder why they wouldn't source their materials from more local modern suppliers then such as in the Detroit area? I am aware that SMS does reproduce their own vinyls and cloths as needed so maybe SMS will give Legendary discounts that we would not see of course so as to compete with the rest of the industry in volume sales. I guess we would need to be insiders to know what really goes on....
My friend in Finland decided to just buy the material from SMS and have his seats made up in Finland by a very good upholstery guy he has available rather than wait many months for Legendary to start being able to supply those seats again.