When I was checking around numerous stereo places for my orange car, they all said none are designed for vertical, although Jack above seems to have found a good one. I prefer the set up with a 10-disc changer in the front trunk along with amp. Precision Pro-Formance can design you a good front trunk shelf set up which look super, and you then run a radio/tape player in the dash. Or, you could customize your dash like my other car the attached site below, and you can run horizontally (not for Pantera purists though).
http://hometown.aol.com/ciao4u2/index.html