Yeah, I remember that connector from the external VFO on my TK-820s.
Check out
http://www.kg6haf.com/kenwood.html
<i>W9GB writes: "Well Kenwood Parts and PacificCalifornia - the 2 parts distributors for Kenwood USA ... have them and still have them ! 9-pin VFO jumper plug is missing on the back panel this is available from Kenwood Parts (E05-0901-05 TS-520/TS-820 9P VFO PLUG)</i>
If they won't sell them to you directly, I can order them through work. Even though I work for an LMR dealer, I can usually get amateur stuff from KW parts as long as I have a valid part number.