I was just looking through the '07 parts catalog, and saw that there is a "Audio
Overlay" kit # 70160-06 listed only for Ultra's. This wiring kit has all of the wires and connections for speakers, controls, cb, etc. that only the Ultra's come with.
So I will hazard a guess and say NO, your Classic does not have the required wires for rear speakers. The part # for a 2013 is probably different.
If you are only interested in putting rear speakers in, and not rear controls, go to the Hogtunes website, and ask them about wiring. They have been super fast and helpful to me. Let us know your outcome.