That is probably nearly the same one I have, Roger, except I don't have Sirius. Mine is a Visteon model VP4DBF-18C815AE. A user manual came in my Monterey packet, but it is actually for a different Visteon unit. The buttons are all in different places, but yet function the same, so the manual is relevant and useful.
The problem is that Visteon supplied radios mostly to Ford and some motorhome mfrs., and not to the public as such. Their site isn't useful since they built radios specific to mostly Ford individual models, and expect you to go to Ford for parts, including manuals. There is a general purpose website for product owners manuals, but they didn't seem to have most Visteon radio manuals. You probably won't have much luck at Allied/Monaco either.
The frustration is that many Fords have versions of 6CD Visteons, yet manuals are hard to come by. Nevertheless, you might try Ford Motor Corporation. The "4" in the model number means it was built in 2004. The "18C815" is common to most of their 6CD models, they hold 6 CD disks inside. The difference mainly in models is designated by the last two characters - most are AB, AC, AD, etc., but good luck finding AE. The AE must be for the model without Sirius Radio built in, or "Sirius ready". The user manual I have is for models with Sirius Radio, as yours appears to have above it in the photo. I don't know which yours might be... AB, AC, or AD. (The radio is actually "Sirius Radio ready", which explains why your Sirius control bar is not inclusive in the radio face itself, but probably hooks up to the radio in the back quite easily and meshes electronically like "plug n' play"). Nevertheless, though the buttons are in different places on the radio face than in the manual I have, they operate essentially the same, so the manual is handy for at least that.
You might try posting a manual inquiry and photo in the thread at the website linked below, and see what happens. Otherwise I can try to scan and email you the manual I have.
http://www.crownvic.net/ubbthreads/ubbthreads.php?ubb=showflat&Number=2242391-Joel