Have you found anything out? I have seen sales brochures from 1911 I believe but that about it. I have 2 of them same units. I even went as far as to track down the correct Milwaukee Tank Works pad locks and keys for them.
Unfortunately I have not, I have seen old photos of the area where it supposedly came, be curious what oil was used in it, I know there was a round sticker on it that is long gone, may even been used for kerosene. Wonder how many were actually made?