430 Help needed to remove rear shock absorber

Am in the process of changing a few suspension components. I was able to remove the shock absorbers in the front and replace the bushings in the shocks.
The rears are a different story. I am not able to figure out what bolt size I need to remove the pin that holds the bottom bushing. The nut is part number 102825 and attaches to the bolt 204974.

I followed the workshop manual instructions.
Image Unavailable, Please Login
In the above picture I am trying to remove bolt (9). A regular 17 or 18 mm socket doesnt seem to work. Is any special tool needed?

thanks!!

 

Thanks for the detailed pictures, very helpful. Yes I have removed the drop link, my problem seems to be figuring how to unscrew the nut, not able to get a socket into the wall.

 

Thanks for that, so the nut is a 19mm? I guess I need a thin socket to get into that notch where the nut is fastened. Let me take another look. No aftermarket nuts or bolts.