We both missed it and you can see why it is easy to get confused.
From the manual and I quote.
New Option: Voice Guide & Storage Unit (VGS-1)
Developed at the same time as the TS-480, the VGS-1 can be
installed as an option. Combining in one unit the functions of the
voice synthesizer unit (VS-3) and the digital recording unit
(DRU-3A) previously offered by Kenwood, the VGS-1 goes
beyond both of these.