Whatever you want to call it Ive learnt that its a nut that can come loose in service so either use locktight or once its done up use a punch to deform the top edge of the tube, dont go over board as you might want to undo it again sometime.
Another tip is before its put on fill the gap between the insert and the strut tube to about 50mm from the top with oil. The theory here is that if an air gap is left it will impede the heat transfer to the outside of the strut causing shocker fade and shortened life. ( the shockers life and possibly yours too).

I'm glad to know this nut loosening off is not uncommon, thanks Ron. As a side note, Koni recommend 50ml of anti-freeze, not oil 

"so if you reused it to retain your new inserts it would still be called a Gland nut."
 
Absolutely correct the original Ford item was a gland nut. And the diagram supplied is correct.
However the photo 70 Capri supplied is a nut supplied by an after market shock absorber company to use with a sealed damper and has no seal or gland. So it is just a nut.

PeterM
"so if you reused it to retain your new inserts it would still be called a Gland nut."
 
Absolutely correct the original Ford item was a gland nut. And the diagram supplied is correct.
However the photo 70 Capri supplied is a nut supplied by an after market shock absorber company to use with a sealed damper and has no seal or gland. So it is just a nut.

hahahaha its now just a nut , you keep missing the point completely. In the trade 'just a nut' is still referred to as a gland nut despite the technicality, so I'll keep calling it a gland nut so my suppliers understand exactly what I actually want without having to describe what the nut does. In the end of the day my intention was to help 70 capri with relevant info, so if he decided to chase up a tool to undo 'just a nut' he will have no trouble walking into any automotive parts shop or tool specialist and asking for a strut gland nut tool, and they will know exactly what he is after. It will probably say gland nut tool on the packaging and the invoice. 
 

For heat transfer the k value for air is 0.024, oil 0.15, water 0.58 so antifreeze would be better than oil but would you trust it corrosions wise?  But for street use do we need to even bother with oil?  No doubt it would be better but is it necessary or a bit of over kill?  
 
I have seen some with a small tack weld on the nut to hold it in place.  Dont forget to put the spacers in the bottom otherwise the insert will rattle no matter how tight the nut is.
 
For the nut name debate the original strut was oil filled with its own piston setup so it was truely a gland nut with an O ring fitted.  Cartridge style inserts are after market and were made to suit the original setup and tooling but I think they call them the retaining nut.  In some shops today the young fella serving you will give you a blank stare no matter what you call it

"In some shops today the young fella serving you will give you a blank stare no matter what you call it"
 
Brings back a memory.
In 2008 when I phoned Ford Motor Company Australia Customer Relations in Melbourne looking for an Old Vehicle Report for the RS2000 I was interested in buying. The young woman I was speaking to fell silent and said she had never heard of an Escort and had no idea what an Escort looked like.
But I have absolutely no idea of the new cars and which/what makes and models that I drive past every day.