Which is why I'm not connecting them in the factory style, in my 1998 that never had them available. ;-) As noted, I'm either going to run new wiring from the head unit, or repurpose some of the wiring from the CD changer that will never be reinstalled. I can solder extensions to those wires quite easily to get from the CD changer location to the upper corners of the D-pillars.
Side note: In a rather surprising bit of convergence, the D-pillar panels with the speakers came from a post-facelift W163 with an Anthracite interior. I figured I'd have to repaint them to match the dark grey around the hatch opening in my '98, since the Anthracite seats, door panels, and console are much darker than the medium grey in my car. It turns out that those trim pieces aren't black, they're the same dark charcoal as used on the 1998-99 models with a grey interior.
