IBM Nixie tube voltmeter?

[Joe R.]

Last week I found a box marked "IBM" "01480" "DC Volts" that has three
Nixie tubes in it. I tested it and sure enough it's DC voltmeter. It's
black and measures roughly 4"w x 2 1/2" x 8". It has a single neon light on
the LH side that acts as a "1" so that it can read up to 1.999. On the side
of the box is a sticker that says API Instruments Model 430 and has the
pinout of the rear connector and some other data. Anybody know what this is
out of or anything else about it?

   Joe