1. 4.6L DOHC 4V vs the SOHC 2V
03's = black valve covers 04's = unpainted (grey) valve covers
2. Different C pillars, similar to the 01 Bullits, curve inward to match the curvature of the side scoops
3. Subframe connectors were standard on these cars, though it doesn't take much to have some welded/bolt on any car
4. Front brakes are twin piston with Brembo front discs (same as 03/04 cobra)
Keep in mind that auto Machs do exist and came that way from the factory. Surprisingly when you do the numbers breakdown by transmission and color the auto cars are more rare. (Though that still wouldn't sway me to an auto)
The interior of course is different having the comfort weave seats, retro gages (same as 01 Bullitt), some have the IUP (silver painted center stack, billet pedals, brushed shifter ball, larger, folding headrests, silver door lock pins). Of course if someone has gone through the effort to mimic a factory Mach to this detail you can always run the Vin...all true Machs have an "R" as the eighth digit designating that it is a Mach 1.
I would say that a clean Mach 1 with 18k miles for 15k is a decent deal, even better if you can get it for less. I paid 10k for my 04 with 58k miles last June and it only needed some minor cosmetic things (cheap factory hood stripe started peeling). So there are definitely good deals to be had.
Good luck and keep up updated!
12 Black GT500 SVT PP l 2.6 Pulley/Idler l Airaid l o/r X l 305 NT555R's l Recaros l
04 Azure Blue Mach 1 / 03 Sonic Blue 3.8 / 14 Sterling Grey F150 FX4 402A 5.0 / 11 GT500 R.I.P.