I completely understand. I did it too and researched the hell out of it along with calling the companies who make them. Others will chime in...take it all in and make your best decision.
edit: I don't have a dart but to the companies that make these..(see my "universal kit" comment)...they don't look at it that way either. That was the concept that stood out to me the most..is how the EXACT make and year of your car isn't so important (to a degree) because it's basically a universal harness.
just one more thing...The value/cost ratio of these universal kits is 1.) you will have (at least with ron francis) a complete wiring diagram to keep with your car 2.) quality of wire (heat and abrasion resistance GXL/TXL) 3.) updated circuitry Fuse box 4.) instructions
