My goofy project ideas and general questions re: Fox vert audio upgrades
 

As I'd mentioned in an earlier thread, I want to upgrade the audio (on a budget) of my 91 LX convertible. I've been thinking along the lines of replacing the factory cassette with a late model Ford single CD, and in fact bought a new takeout from a 2008 Grand Marquis off eBay. It fit my idea of a low profile unit that looked close to stock( I am no fan of the busy,attention grabbing multicolored ergonomic disasters that are most aftermarket head units) and wouldn't leave me with a hole in the roof when I park it. Reasonable fidelity and decent volume at a reasonable cost are my goals.

My plan was to adapt a harness for the Marquis to a Mustang harness that would snap into the factory plugs, then adapt a new outboard amp into the spot of the old amp and tie into the existing speaker wiring(replacing the speakers as well).

The fly in the ointment: several Crutchfield advisors say " Can't do it" because they don't have such harnesses(and certainly don't want to assume liability); a very helpful advisor at Metraonline.com said no harness exists for the amp, and it can't be done anyway because the Mustang has a common ground audio system.

That's it think I, aftermarket it is, and I'd resigned myself to pulling new wires with all the free time I don't have. I like the understated look of the Nakamichi CD300, and at under $200, it's in budget. Unfortunately, getting a stock looking green display I want means doing something crazy-cool like this guy-http://forums.bimmerforums.com/forum/showthread.php?t=533691.

So, for grins, and at long last getting to my main question, I started reading the stereo section of the Ford shop manual. It describes the 'premium' audio setup as having separate return wires(the front dash/door speakers being in parallel share hot and return wires), and it sure looks like that's the case from the wiring diagram. So if these separate returns go back to the head, is that a common ground setup? Am I misunderstanding this?

Second batch of questions: if I do end up going aftermarket and pulling new wires, how much of a pain is that? I'm only utilizing stock speaker locations, no subwoofer. If I utilize a reasonably powerful receiver can I avoid the extra amp? Any speaker, amp or head recommendations?

Thanks for any help those vastly more experienced modders can provide!

One last note; The impetus for this project came from my 5 year old who would rather take the van to school so she can hear 'her music' and my wife/budget guardian whose first reaction when she took her first ride was 'You're going to do something about that crappy stereo, aren't you?"