Hi Ronnie, and welcome!
Have you checked with the RV dealer at the NE corner of 635 and 35N (forgot their name, sorry!)? We have been there several times when we lived in Rowlett for Excella parts (got a rib from them to clamshell the back end for a car hauler, and some other stuff) and they always had several units on the property, either for sale or for work to be done. I believe they are a certified Airstream dealer. I hope they are still there (lots of construction in that area), but if not, you should be able to find where they moved pretty easily.
Good luck with your search, and happy camping!