I think the SHM book outlined the difference, but there may not be one - it's from five years ago so I am a LITTLE rusty on specifics, but this may end the debate:
This is a quote from a man in the know from another site but was basically the same write up as SHM
Let me provide a history lesson here to the uninformed.............
Back in 1996-1999, the aluminum heads and blocks were cast at a foundry (TEKSID) in italy, the same manufacturer of aluminum blocks and heads for Ferrari. Threre are a few reasons why ford, at the time outsourced production on these pieces. They did not have the experience and knowhow on the casting technology and engineering aspects of a durable aluminum block. Ford ended its contract with Teksid in 1998, enough blocks were produced for the 1999 run. Ford tried to get into the aluminum block design and foundry process in 1999 and released the "explorer block, or more commonly called the "mountain" motor. It had extra material around the outside of the cylinders and in the valley of the block. The problem was not the engineering or cast shape or amount of material that the explorer block had over the Teksid block. The metalurgy was incorrect and fatigued at the 700 rwhp mark. The explorer blocks cracked in the valley and in between the cylinders. Several proven racers like Joe Stewart, Dave King, Bob Trianese, Tim palmer, and John Mijovitz have identified the shortcomings of the "explorer" blocks and have found that they are useless after 700 rwhp mark period. Not One Teksid block had failed due to too much horsepower.
Moving forward.......
With the 2003 cobra in the drawing board, ford found that its current technology with aluminum blocks did not meet the durability standards that they desired (remember this is basicly the weaker Explorer block not the Teksid block). They went with a GT romeo block that was CNC machined for straightness, thats it. They have 4 mains, not six. The cobra crank was carried over from the previous versions.
The only reason why the 03 cobras are so stout is the manley rods and the forged manley pistons.......If you put those components in a 96-98 block I can guarantee you that the aluminum block will hold up to any cast iron block in fords inventory.
Now if you look at the recent hot rod magazine, you will see that ford invested huge capital on the CNC machined aluminum blocks that have found their way in the GT40. They have finally got the foundry process right. If aluminum is so weak, why is it in a car capable of more power than an 03 cobra? I need not go on with this any more.....................
So your 01 cobra "teksid" block would not appear to be a stock part on the cobra if you follow this above information...that's why I posted on this thread to begin with...to inform...
Check out this Bullitt that MPH installed a twin 57mm turbo kit on with an 01 Cobra block: http://www.turbochargedpower.com/Movies/BCsTTBullittnomusic.wmv
