Your best bet on this one is
www.car-part.com - they're a nationwide link to junkyards. Sometimes you see new parts listed, too.
Otherwise you're pretty much in the dealer territory for body parts and light assemblies: there just is NO aftermarket for that sort of stuff.
www.gmpartsdirect.com (Flow Chevy/Cadillac, Wonston-Salem, NC)
www.gmotors.com (Palm Chevy/Cadillac, Gainesville, FL)
Luke, in Parts at Lindsay Cadillac over there >>>>> (Alexandria, VA (near DC)
BTW, go up and read the entire Cadillac Technical Archive in the black bar ^^^.
Wade through as much of this Forum and down in Northstar Performance as you can.
Study the sticky on the Seville/Eldorado main page titled "How to pull codes". Your car already has a complete built-in code memory and readout system. You want the procedure for the OnBoard Diagnostic OBD-I protocol. You MAY have some OBD-II codes because 1996 was the changeover year.
