The minimum for a good tube is 24, and this tube tests at 36. The date code is 813, which I believe is 1958.
Item Tag: 1 tube
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Western Electric Type 352A Radio/Audio Tube, Strong
It is a good strong tube. On my military TV-7D/U tester the minimum for the output section is 16, and this one tests test at 26. The minimum for the diode sections is 40 for each plate, and these test at 50 and 53.
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Western Electric Type 421A Dual Power Triode Tube, Good
This is a used tube which tests strong. It tests at 52 and 58 were the minimum is 40 for each plate on my military TV-7D/U tester. It should be great for your project.