See
http://www.peachparts.com/sportline_suspension.htm
If you have the full factory Sportline, there should be a "Sportline" logo (including an AMG-like reducing trapezoids symbol) on the top of the gearshift (and, unless debadged or a '93 Limited Edition, "Sportline" emblems on the sides behind the front wheelwells). The Sportline suspension (or parts thereof) may have been added aftermarket, in which case you would not have the gearshift logo.
Call Phil at Fastlane for further info.