No, there are a couple of sizes. I think I got the big ones that are from the Speedy and/or America (4.5 x 10.25"), yes; confirmed. The only thing is that the 2 lower holes on the fixed part (bracket to bag) bracket fall lower then the stock bracket holes in the bag when in contact with the molded plastic backing of the bags. This neccessatates a 1/2" spacer between the lower bracket holes (2) and the holes drilled into the bag backing by the customer. The top (2) holes line up perfectly. With spacers in place it looks as if they were made for the Thunderbird. After installation, one side of the bracket is fixed (or not adjustable) to the bag but the other side can be loosened up with bags attached to move forward or backward on the bike. Hence, the term "universal" or "adjustable".
Heres the link to the big ones I got (10 inches long) (the biggest)
http://www.ghostbrackets.com/content/view/349/83/
As you can see in the picture, there is plenty of room (via long slots) for adjustment forward and back. The hieght is predetermined by the stock top holes in the bag already there. Theres no measuring or guessing after you mount the top hole bolts on. After that you just drop a marker thru the bottom holes to mark your 3/8" drilling spot. I think they even come with 2 weather tight plugs to fill in the stock lower holes in the bag.
The only fittment I can think of (by Edge) is if they totally redesign the bracket so no drilling of the lower holes into your bags is required...ie. no spacers. The market is so small, I'd doubt they retool for this bike. They've gone out of their way to make this part universal. Just check the part numbers for other bikes. They only make 2 or 3 sizes to accomadate most bikes.
They told me the same thing Todd (6 months ago). I think what they mean is that they are going to add the Thunderbird to the website as an application their existing product (4 1/2 x 10"). I could be wrong but thats what Alex told me last fall. He requested pictures that I sent him but they never used um.