When I needed a black tank for my 2004 28.5 Jayflight I called Jayco with the VIN and they told me I had to order it through a dealer. They gave me the dealer's name and I co-ordinated the order through them. When it came in I picked it up so that I could inspect it before accepting.
If you are interested here is a link to my 2013 post about the project:
https://www.jaycoowners.com/forums/f...nce-13709.html