405 front suspension struts

Hi All,

Having looked under the plastic covers that fit on top of the front 
suspension struts i've found something a bit disturbing.
The top-nut on the left strut had turned loose quite a bit. The nut on the

righthand side is also quite loose.
Maybe this is something that just happens (car has done 280000+ km), but 
it 
doens't feel very safe, but probably explains the noise when making
corners. 
So my plan is to tighten both nuts (if needed), preferably to the correct 
torque setting.

Can anyone confirm thats these nuts are called "Suspension strut upper 
mounting retaining nuts" and that that should be tightened to55Nm?
(I've been looking at Haynes (ch 10) and found a table with torque wrench 
settings, but I don't want to overtighten something.)

Thanks!

Ed