ER, you might want to take a look at the DX398 again.
I have mine in front of me and it certainly does have
SSB mode, support for both LSB and USB.
I modified mine to defeat the tuning muting, but
even with that, I just barrowed my wife's stock
DX398 and I can tune it just fine. I prefer the lack
of mute,.
On the lower right front there is a button labled
am/mode. This toggles/steps the radio through
AMLSBUSBAM.
Again, please recheck your "facts".
Terry