My guess is buy the newest model you can find that fits your criteria. Transmissions are improved with "tweeks" yearly. I'm not sure about their computers from '97-'04
Stuff I found on the web.........
Key notables for the LS1 include a switch to a more powerful PCM in 1999
which is more tuner-friendly for you computer hackers out there. In
2001, they then received the freer-breathing LS6 intake manifold and the
LQ4 camshaft for a total of 350 horsepower. The 2001-2004 ZO6s all had
great heads, cams, and engine/drivetrain packages, making them the most
desirable and as expected, the most expensive. Over time the 5.7-liter
LS1s and LS6s have proven to be incredibly reliable, efficient, and
powerful. The main thing to look for is weak oil pressure on early LS1s
and signs of abuse, which typically show up as oil leaks and odd engine
noises. These cars hardly ever spew a drop of lubricant but dances with
the rev limiter, missed shifts, and general lack of LSX respect will
also result in piston slap on cold start and lifter noise. Documented
maintenance records help, while frequent oil changes with quality
synthetic lubes promote engine life.
http://www.superchevy.com/how-to/0905gmhtp-chevrolet-c5-corvette-overview-and-buyers-guide/
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Only 32 years together