All GT's from 1999 have T/C and ABS. The interiors and wheels are the only differences. The deluxe has standard cloth, no Mach 460, and the '99 style 17'' wheels. They started two levels in 2001 at the earliest. The premiums came with fleather, Mach 460, and Bullitt style wheels. For 03/04 prem you could get optional 'bright alloys' which were the 99-01 Cobra wheels. You could upgrade your deluxe with options like the Mach 460, or leather. Most were built with plain stuff only. I can't think of any deluxe's with upgraded goods. It was cheaper just to buy a premium if you wanted that stuff. The Mach 1000 was only for premiums. The reason behind the two levels is because it is faster and cheaper to build cars as packages, not individual optioned cars. Most auto makers realize that the majority of people who upgrade things want it all. Those that like plain cars don't want any of the stuff. Just be glad Ford quit putting 16'' wheels on base GT's. I have all the brochures from 1994 to 2004.