The difference, Twin Cam?
 

What's the difference and the meaning of
twin cam (camshaft)?

And I still need pictures of the mustang protype for 2003-2004. What issues are those shots in?

Twin cam refers to engines that have 4 valves per cylinder and thus need 2 cams per bank of cylinders to actuate those valves.

It helps to think of a DOHC (twin cam) engine as a quad cam since it actually uses 4 overhead cams. Two cams in each head, one controls the exhaust valves, the other controls the intake valves. Way back in the 60s Ford actually made a SOHC 427 but it was only for racing....never saw a street car. So when did Ford get it's balls lopped off?

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1984 1/2 GT350 (#842 Hatchback w/ T-tops), 302HO, Comp cams Xtreme Energy cam, Carter 625cfm carb, Weiand Stealth intake, MSD distributor, MSD coil, FMS 9mm wires, 1 5/8" MAC unequal shorties, 2 1/2" MAC Prochamber H-pipe, Flowmaster 2 chambers, KYBs, 16"x8" 4 lug Cobra Rs, Falken 245/45ZR16s

So I pushed it up to 110,
That flathead motor was about to give in,
I crossed my fingers and prayed to the lord,
Don't let me down you fuct up ford!"

"5-Oh Ford" by The Reverend Horton Heat