You can buy the adapter from allelectronics.com for about $4. It is my personal opinion, but having full frequency audio out of an amateur transceiver is not a desired attribute.
In fact, I built in a passive audio filter in my mobile speaker to cut out all of the highs over 2.5 kHz, and most stuff lower than 800 Hz. After all, SSB is not suppose to be HiFi, and if you REALLY want to be able to hear weak signals, it's best to limit any frequency outside of about 400 and 2,200 Hz.
Alan, KØBG
www.k0bg.com