The mk1 996 runs from 1997 to 2001, you will see that there are two different type of headlights on the 996, ones that look like the ones on my car which is a mk1 and the ones on the mk2 are a different shape. There were two variants of mk1 996 one with 296bhp (1997 to 1999) and from 2000 to 2001 they got a slight update to produce 300bhp. The 3.6 in the mk2 brings an extra 20 bhp to the mix.
If your interested in failure rates this thread is a good read from a cross section of 911uk forum members:
http://911uk.com/viewtopic.php?t=100994
IMO the weakest point on the mk1 are the heads and cooling system people neglect the cooling systems and the engines run hot. There were also casting issues on the heads which causes the left hand head to crack at the mounting point for the hydraulic tapets across core plugs. Funny thing is even though the castings are the same both sides the problem only ever happens on the left. I would hazard a guess that the figures for the head problems are somewhere in the region of ims failures.