These are the installation instructions for the HD saddlebag speaker kit used in this project:
http://www.harley-davidson.com/en_US/Media/downloads/Service/isheets/-J05386.pdfYou'll notice under the "Installation Requirements" on the first page that it says that a "Radio Harness" or "non-Ultra Overlay harness" are required. These harnesses provide the connection from the kit's audio harness for the rear speakers to the Harman Kardon radio's pin-outs for the rear speakers.
However, since the SESG2/3 already have a connector plugged into the back of the HK (for the iPod module) that would otherwise be used for the Radio or NUOH harnesses referenced in the kit, an alternative way to access the rear speaker pin-outs while also supplying connectors for the rear speakers to the kit's harness is necessary.
What TIF2, Rich, has supplied are the harnesses/parts to retain the OEM plug in the HK radio (by simply adding the 4 wires to connect to the rear speaker pin-outs of the HK radio) as well as the mating connectors for the rear speakers for the kit's harness.
I add this info not to detract from what the OP and Rich have done, but to assist others considering a similar project by providing some additional information.
Nice project and thanks for the pictures.
Carl