Eighty years ago, there was still a shortage of tubes. But if the tube in question was a rectifier, then the serviceman had a solution to the problem, namely, the selenium rectifier. This ad from Federal appeared in the September 1946 issue of Radio Retailing. It noted that even though the selenium rectifier was cheaper than a tube, it would actually last longer.

If you need to replace the selenium rectifier in an old circuit, you can probably do a better job with silicon diodes.  But if you want to keep the original look, like anything else, you can find NOS (new old stock) selenium rectifiers on eBay.

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