Info Please on AC spark plug WR-43

[aball]

I recently found 2 old spark plugs. They are in a hard tube with a metal cap. The tube is marked AC spark plug - 1 Type -WR-43 - Contract NO. DA-20-113-ORD-123664 and they are dated June 1953. I had never seen a spark plug in a tube like this one so I did a google search and came up with this website. Are these spark plugs for a military vehicle? Thanks in advance for any help.

 

[porkysplace]

Spark Plug Info for M37 and Other Vehicles

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