Looking for some assistance from anyone knowledgeable in 1930-40's-vintage aircraft.

I've acquired an interesting fluid flowmeter that I've since determined to be a Rotameter Anti-Icing Fluid Flowmeter to titrate the flow of anti-icing fluid to the propellers. From a 1940 brochure from its manufacturer (Fischer & Porter), it was used in a dual-engine aircraft, and it shows a DC-2 or DC-2 on its cover. I've not found this instrument in any photo of instrument panels from those aircraft, and I'd like to substantiate its use in that aircraft or any others from that era.

Any help is appreciated!

The instrument is here
Name:  DSCN7327.jpg
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Also more photos are here, as well as a photo of the sales brochure:
https://cdn.shopify.com/s/files/1/13...G?v=1481913616