The difference between the 17mm and 20mm might be due to differing diameter strut rod fitted to the V6 (and possibly Activa).
The high pressure hydraulic feed into the strut top, visible in the photo, looks like the larger diameter which means it is fitted to Hydractive models.
Hope that helps, but I'm sure someone will correct the info if I'm wrong.
ok thanks that would make sence! hence v6 activias are s1 and s2....well done mate
right have just been down engineers with my s1 nsf top...measured to thread and pitch and non hydra is m8 x 1.5..took the pipe off my strut and measured it its hydra and the thread is m16 x 1.5...also measured the length,diameter of the pipe end...around the olive so by morrow he will have it sorted..but im a little worried thinking about it cause i checked the nut size on top of my strut and its 27mm...i HOPE its not a reflection of the coller size
99 silver 2.1td exclusive xantia
99 red 2.0 hdi exclusive xantia..
00 black 2.0 hdi exclusive xantia
99 blue 2.0 hdi exclusive xantia
06 silver 1.6 hdi vtr c5
57 blue C4 GP 1.6hdi exclusive
08 black C4 GP 2.0hdi vtr
ok guys i gota say this kingas really are a great company...theyve had plenty of time for me today and theyre help has been outstanding...dont hesitate to email them very helpfull
99 silver 2.1td exclusive xantia
99 red 2.0 hdi exclusive xantia..
00 black 2.0 hdi exclusive xantia
99 blue 2.0 hdi exclusive xantia
06 silver 1.6 hdi vtr c5
57 blue C4 GP 1.6hdi exclusive
08 black C4 GP 2.0hdi vtr