A table radio the Old Man had that he gave me, along with a box of others including the 56X. It's actually very simiar in styling to the 56X, but seems to me to be a little down-market. It came out in 1947 and also appears in Rider's Perpetual Troubleshooter, Volume 15, RCA page 15-62. Unlike the 56X, it doesn't have the tone switch (big deal), and it doesn't have the separate oscillator tube, so it's a traditional All-American Five.
12SA7 - converter
12SK7 - IF
12SQ7 - 2nd det / AVC
50L6 - Audio out
35Z5 - Rectifier
Dial lamp: #51 6-8V, 200mA
I fired it up and it worked but with atrocious reception; it picked up only a couple of the strongest local stations and spit and hissed and was noisy all over. After fussing with it a bit, I realized that even a slight touch where the loop antennas connected to the wires going to the tuner resulted in all sorts of racket—like wadding a piece of tinfoil amplied a hundred times. I remembered this from another radio, so I resoldered the connections with fresh solder and that quieted it down tremendously.
After that, an IF alignment and adjustment on the tuner caps brought the performance up.
All in all, not a bad little player. Biggest problem now is that it's missing one of its knobs (the on-off/volume). There are few things sadder on a radio than mis-matched knobs.
Current status: works fine. Needs a proper on-off/volume knob.