Nuvi 660 - FM Transmitter

Found a new use for an old product. I have experienced some problems with the FM transmitter going across bridges with interference, etc when listening to audible books.
I had an old cassette cartidge that allows a device with a headphone jack and a cassette player to play through the stereo system - plug this into Nuvi's headphone jack and insert cartridge in the cassette deck and you are good to go. It doesn't work unless you are listening to something - that is not just traffic directions - does not have enough activity for the cassette to stay connected.

http://www.radioshack.com/family/index.jsp?categoryId=203232...