An unusual American SSB/ISB adaptor, for use with communications receivers, was the General Electric (GE) YRS-1 of 1948. This was apparently aimed at both the professional/commercial and amateur markets. It was described in several magazine articles of the time, of which two are attached.
GE YRS-1 Electronics 194807.pdf
GE YRS-1 WW 194807.pdf
It used a locked oscillator for local carrier regeneration, and the Norgaard phasing method (with Dome phase-shift networks) for sideband separation. The output could be switched to either sideband, locked oscillator DSB reception, or to “normal” reception using the AF output of the associated communications receiver. Nonetheless it is evident from the schematic that the separated sidebands were available simultaneously, so it could have been used for ISB reception.
Locked oscillator DSB reception was in fact exalted carrier reception, of which Crosby was a major exponent of the time. However, Crosby used reconditioned carrier rather than a locked oscillator. And although his patent (but not his 1945 paper) showed the possibility of sideband separation by the phasing method, it is not clear that it was actually used on any Crosby receivers. Press Wireless also made exalted carrier HF point-to-point receivers in the later 1940s, and these did use a locked oscillator for carrier regeneration, but as far as I know did not include sideband separation.
How well the GE YRS-1 worked, or how long it remained in production is unknown. But its technique turned out to be well away from what became the mainstream vector for professional SSB/ISB receivers, namely the use of IF filters for sideband separation and carrier extraction, along with AFC loops.
One could say that the YRS-1 presaged the PLL synchronous, selectable sideband AM demodulation technique that appeared (at various levels of execution competence) in amateur, domestic and semi-professional HF receivers during the 1980s. Professional point-to-point SSB/ISB receivers appear to have stayed with IF sideband separation and carrier extraction filters and AFC loops, although in some cases in the solid-state era, PLLs were used for carrier regeneration, an example being the Eddystone EC958/12.
Cheers,