Here is the complete system. I had to buy a new FM modulator, as whoever sold the system had removed it from a car and left the main part of the FM modulator in the car. It was only $20 from Sirius.
The installation is very easy. I slid the radio out and connected the FM modulator between the radio and antenna. The control head and the FM modulator each have 6m (~19 feet) of cable and the antenna has 14 feet of cable...plenty of cable, even for my crewcab truck.
I decided to put the main unit behind the rear seat. Space is at a premium so I velcro'd it to the stereo amplifier. There are only 3 wires to connect...constant +12V, key-on +12V, and ground. All are available at my wiring panel.
I velcro'd the control head to the dash.
Update 12/26/2004 - I moved the control head to where the FT-7100 head used to be.
Many people have had good results by putting the antenna on the dash. I'm gonna try it there. I can't see this antenna being strong enough to stay on the outside of my truck.
I connected all the wires, turned on the radio, and...it worked! I signed up online for service.
So far I really like it. My drive to work is very rural with lots of hills and valleys. The normal FM station I like to listen to fades quickly. The Sirius radio doesn't drop out at all, and the sound quality is great. Howard Stern has signed with Sirius so soon I'll be able to listen to him in the mornings.
I like the display of artist and title. I also like the many different types of music and information channels. Just the thing for a nerdy engineer.
Update - The dash mounted antenna works okay, but I can tell it would work better if it could 'see' more. I have replaced it with a flat external antenna.