The self contained circuits containing resistors and capacitors were often
used in the audio chain of receivers. Many schematics show the contents of
the integrated circuit at the side of the schematic - but if not, it is easy
to go to any tube design handbook and reverse engineer the components. As I
recall, all of the RCA tube handbooks contain the elementary design data
needed to determine how the chip should have been constructed.

Certainly not rocket science.

Colin K7FM