996 is the Porsche internal model designation for the model year 911 in question.
901 - first 911 - 0 in the middle trademarked by Pugeot - so changed to 911
911 to 1989 when c4 introduced
964 model designation for 911 from 1989 to 1994
993 model designation from 1995 to 1998
996 model designation from 1999 to 2004
997 model designation out next year
BTW - they are all 911's...
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"If you can make black marks on a straight from the time you turn out of a corner until the braking point of the next turn, then you have enough horsepower"
-Mark Donohue
