I can't think of any modern tintop that uses left and right hand threads on the axles anymore. I don't think it has any effect on the end of a tight fitting splined shaft, either. The point of maximum torque typically applied to the axle would be in first gear under full throttle, that would cause the right hand wheel to resist the clockwise motion of the shaft slightly in the splines, loosening a right-hand threaded nut if there was any movement. Basically if the thread direction was important, the right hand shaft would have a left hand thread and vice-versa, the opposite of what the car currently has.
In reply to #40 & #41
Yes, I've spent over 20 years in the Peugeot world & so was thinking about doing drive shaft nuts & obviously I've not removed a rear one on the 7! As said above #42 the shaft is a splined fit so it just makes different hand threads overkill.
That said, I've always found the float test confirms the decision to fit new!
Liz & David
Just for reference. The Ford original parts are still available from your local Ford dealer. 6133689 and 6133688 are £16.60 (including VAT) each. The only downside to using the Ford original part is they have changed the spec from 41mm to 42mm, so you may need a new socket. I discovered this last year when I built my car. At the time CC supplied one 41mm nut, in older Ford packaging, and one 42mm nut (with a packing date of November 2017). Now both are now 42mm, one was still packed November 2017 and the other was May 2020 which suggests they are still produced. .
My detailed build blog
Thanks everyone, helped greatly by a 2 foot breaker bar with a 70 kilo lump on the end of it, the job is done.