If you have the Saab sat nav, you need a real shark fin. Otherwise a dummy will do. I bought a cheap FM aerial and left it unconnected.
The original will probably have a phone aerial with a wire to the front, but it's not needed in the modern day with Bluetooth car kits that use your mobile phone's own aerial. Built-in aerials are no longer needed. Phone aerial technology is way ahead of where it was in 1998 when the shark fin was introduced.
Changing a shark fin in the estate is easy. Go in under the headlining through the tailgate. Pull off as much plastic trim as you need to around the tailgate. Undo the two plastic fasteners in the roof - they are quarter turn. Then reach in and undo the 22mm nut that holds the fin.
