I'm no expert but did have a good look at the LTS bikes back in 97/98. The DS moniker in GT speak is "Dual Sport", which meant generally beefier spec, longer forks (some even dual crowns) and later also disc brakes. I'd say what the market labels as enduro or all-mountain today?
The XC models by comparison had lighter spec and shorter/lighter forks. I don't know if the geometry of the XC frames was also different. Longer top tubes and angles corrected for the fork travel would be ideas. But surely someone with more specific knowledge on the GT line will chime in.
And post up a complete picture of the frame, colour in the detail looks good.
Enjoy!!