Original radio was one D700 which has remote control head which was placed in front of the ash tray. While this worked it was hard to see and adjust. When I had the GPS on the dash it got too much sunlight so a new solution was needed.
I made a plate out of aluminum in the shape of a "T" with the stem mounted to the dash using the two screws holding the car display (date/time and warnings) above the ash tray. Since this had a slope I needed to bend the metal just some, still keeping some angle to keep a good viewing angle.
This picture shows the D700 head and the GPS unit mounted on the metal plate. There is enough room behind to adjust the air controls - but not much.

side angle plus extra radio mounted on center console.

The D700 radio is mounted under the rear seat (right side) with the control wires under the carpet and console. To access under console remove the lid and CD bucket to allow easy access. A hole was drilled through frame at front edge of seat for control wires. The power went under molding and carpet along right side of car and through a hole behind right kick panel. I used path along with other car wires.

I added the air tube to have the radio draw new air from under the edge of the seat. There is plenty of gap under seat but needed fresh air intake since I was using GPS.