Found this in a car. Could it be an original once used spare?

Yes. Especially if there's a film on the rubber and the tire size is a 165.

can you find the tire MFG date code??

It's the right tire but if you want to be sure you need to find the manufacturing date.
Hard to see in the picture, but the SS pattern on the sole is what you're looking for.
Unfortunately, you should never drive on that tire. The runber its too old and unsafe to drive.
I have a couple of them at home.

Lol. No intention of driving on a 40 year old tire. Wrong size for my spare anyway.

I've got the original spare tires from both my '71 and '73, never used but dismounted from the wheels.
Never going to use them, but just couldn't throw away. Would give them to anyone needing for concours etc if they pay shipping...

(both 165 Dunlops)

Kurt,

Looks like a Dunlop SP57 from back in the day on a 73> steelie, so could be either a factory spare or a dealer swap-out theft of the alloy spare.

Don't forget supper next week Mon eve. at Bankok Thai!

I'll be into to TUL then straight down to Sallisaw on Sat, but back up to Tulsey Town on Monday at some point in the day after meetings.

Cheers!
Tom
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On my calendar Tom.