Apologies if I've misinterpreted the explanation; but why do we think the "mystery box" in AE's cockpit is possibly a Bendix Type MR-1B remote control for Bendix RA-1B receiver, as opposed to a version of the RA-1B receiver itself (or a visually-similar box) ?

Mystery box

MR-1B remote controle

RA-1B receiver
Note the knob in the upper right on the RA-1B receiver, bisected by a white, straight line, which has the option of being set to "local" or "remote." It may not be possible to tell in the "mystery box" photo, but the knob that most resembles the RA-1B's local/remote knob in AE's photo may be set to vertical. At any rate, I believe in the case of remote/receiver combination radios, it is the receiver which contains the control for local/remote, rather than the remote.
Here is an example showing II believe) a 1941 RA-1B remote/receiver combo:

Caption reads: RA-1B receiver is a communication receiver designed for use in aircraft. It may be employed for the reception of continuous wave telegraph or radio telephone signals within frequency ranges of 0.15 to 1.5 mc and 1.8 to 15.0 mc. Free band are used to give full coverage in each frequency range. Aural direction finding and loop antenna reception may be optained over a frequency range from 0.2 to 1.5 mc by using the receiver in conjunction with the Bendix direction finding equipment (DU-1).
Do I have this right - is the little guy the remote, or is that the azimuth unit?