Older articles exist - check Dirt Bike and Dirt Rider archives. At least three specific article tests exist based upon memory. The basic engine and drive train has not changed since 98: USD forks, triple trees, ignition advance curves, shock, hydraulic clutch, and swingarm upgrades have been made.
The "new" 98 380 likely in Sept - Dec 97 time frame. The changes for the 99 380 model as tested by 'Lumpy' over a 3 day 300 mile trail test. A shoot out between the open class bikes - comparison to CR 500, KX500 if my old memory is correct. Believe there was also a fourth article based exclusively on KTMs riding in Eastern Wood conditions.
My '98 380 EXC is a great bike - I love it for trail riding, hill climbing. and play racing with friends. If I was a serious racer I would opt for one of the smaller displacement models since the 380 can be a handful when on the pipe for an extended length of time through any sort of technical riding area.
IMO - articles on the 300 are also applicable to the 380 concerning fork and shock performance reviews since other than displacement related factors there are few handling differences.
Good luck in your search!!