From the shock I removed the rubber snap-cover, the nut and large dish washer -- but recessed into the upper rubber bearing is another nut that requires a 17mm wrench.
Though I'm sure there is a special tool available, I'd appreciate any short-cut ideas on how to remove it. I think it's unlikely that a cut-out socket (like the 21 / 22 mm used on the Front Struts) is used -- there's only about 1/2" clearance between the top of the shock piston rod and the speaker shelf metalwork.
Thanks!
Jim