Hey Dave,
I've been researching the same kind of thing for my '47 panel. I can Email you a couple of pictures that may help, but I don't have a website to host them so I can't post them here. I may also be able to dig into my Email archives and let you know who had a tank that I didn't buy.
One of the pictures is a photo that a guy sent me of the gas tank hanger hardware from his AD Suburban. They are the earlier type that nest inside the right frame rail and mount the gas tank between the frame and driveshaft. The other is a diagram from a "Factory Assembly Manual" that I bought on-line. The book isn't really an assembly manual, more like a collection of drawings from 1953, but still very useful. This particular drawing is the detail of how the tank is mounted (panel and Suburban again) between the right frame rail and the driveshaft, suspended from two braces that span all the way across the frame and bolt into the top of both the left and right rails.

Don't lose your head to save a minute,
You need your head, your brains are in it.
Burma-Shave (1947)