That is most likely a proprietary extrusion for each company. The dies are fairly cheap, and your minimum run could be as low as 1000 lbs. as sreid pointed out. You can get a lot of info by calling supply house/distributors in your area and describing what you want. They will find all the close matches for you. If that doesn't work try these:
The Aluminum association, Alro Metals, Alcoa (try web searches).
Hope this helps...