This is the earliest known to me Stereo Realist camera. The Serial Number is only A0029. This is the 29th Stereo Realists produced, out of 130,000.
In addition to all the features shown by very early Realists (coarse leather, lack of witness marks in right film gate, lack of sprocket guard, and, of course, Ilex lenses) this Realist has two features not seen before in a production cameras:
The shutter speed dial goes up to 1/200 (not seen in a 3.5 Realist) and has large numbers for T, B, 1, 2, 5, and 10 shutter speeds). This is the same shutter dial has only be seen in an Stereo Realist advertisement dating from 1945, two years before the camera was made available to the public. The serial number is not at the bottom but it is stamped inside the camera body. This has not been seen before in a production Realist.
There might be other changes too, but these are the two changes that jumped out when I first looked at the camera. I have only owned this for 30 minutes so far.
If you know of an equally early or even earlier Realist, I would love to hear from you!
Updated: May 2010