Did you know:

It's possible to replace the 26x6 tubes in the R-392 DIRECTLY with 40763
MOSFETs?

I tried it as a joke of sorts, but the radio seems to work just fine, and
the current draw drops to almost nothing.

You can also plug in most any NPN transistors in place of the 12AU7
multivibrator.

Of course you don't get that nice hot-tube smell, but you can't have
everything...