In answer to your question, yes you have become accustomed to the quadrophonic sound and your mind recognizes the music most aptly in that state. However, fading your stock system to the front is hardly a good indication of how a quality front stage should sound. People all too often make that misguided and simplistic rebuttal to front stage only. Some people simply prefer the ambience of speakers all around, but often that is due to lack of exposure to a quality alternative. Think about most highend home speaker arrangements: two large floorstanding speakers or monitors in front of you. Other speakers come into play for surround applications. The world's best cars are appraised as if the dashboard were a stage, and you're sitting at a concert. At a concert, sound emanates from in front of you. If you're not used to listening to sound a certain way, then a true SQ application will sound alien to you. I am a strong proponent of big power to components and dedicated midbasses upfront. Subwoofers can be added for thaat sub 60Hz or so low end. If you're set on rear speakers, I'd suggest a lowpassed midrange to keep the vocals and soundstage from smearing too heavily to the rear.
Especially in a Ford truck, rear speakers are superfluous. You will need either larger components or a midbass + the 4" speakers to keep up with that heavy bottom end.
Especially in a Ford truck, rear speakers are superfluous. You will need either larger components or a midbass + the 4" speakers to keep up with that heavy bottom end.