I had a friend in my home town whose family had an RCA color set like the one we are discussing (I recognized the control panel). Their set, however, IIRC, was in a large and heavy console cabinet and probably had a stereo record changer plus AM/FM radio.
This particular TV chassis must have been used in several different styles of RCA TVs in the '60s-'70s -- consoles as well as table models, with the former having a separate stereo amplifier chassis through which the TV audio (as well as that from the TT and AM/FM tuner) was routed. Not such a good idea, IMHO,
as when the amplifier failed for any reason it not only silenced the stereo audio, but the TV sound as well.