Looking at the second operator from the right, there appears to be a cluster of four knobs just below the LINE meter.  That fourth knob would be the CHANNEL SELECTOR which would make the radios  R-391s.

Jim

-----Original Message-----
From: Tom B <[email protected]>
To: [email protected]
Sent: Thu, Sep 8, 2022 1:43 pm
Subject: Re: [Milsurplus] Can anyone ID these Aussie HF Intercept Receivers (used in Vietnam)

The photo looks strange but they they are all R-390 or R-390A.  There is something mounted above them.  Maybe a TTY demodulator.  I am not sure.

Tom

On 9/8/2022 2:10 PM, Brian Harrison wrote:

(the gent at email address below didn’t know specifics)