Warbird Information Exchange

For awhile I've had these two Manifold Pressure Gauges and lately I have been trying to figure out what they came form.
I have been using a combination of my RAAF Instrument Schedule and google image searches but nothing has come up.
The serial appears to be 1919-1B-A1
However on my Instrument schedule there is a serial 1919-1R-A1 so maybe, because the serial is slightly covered on the gauges they could be the same gauge, ecxept the 1R one says its a 10-50 gauge or something simliar, while mine is -15- 25. Through all my searches I've never seen a -15-25 gauge?
Is it possible some previous owner has rubbed out the letters and made new ones for whatever reason. But what gauge are they trying to impersonate. It all has me confused.
Any help would be great

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Always in the market for P-39 or Beaufighter parts