The need to extract my rear strut inserts had me facing the same challenge as many other owners needing to replace the struts on their classic Z, removing the dreaded gland nuts. More often than not they are seized on due to years of use. Worse, it seems to be the best method for getting them off by using two opposing pipe wrenches can also be the most damaging. I went through this same exercise with my 1972 lime green 240z several years ago and vowed this time would be different. I remember seeing an workshop manual showing how these were installed at the factory using a special made socket and wrench. I searched for a long time to find an 8-point socket of any kind that was 51mm or 2 inches in diameter. I was hoping to find an axle socket but after many days and nights of Googling and searching I came up empty handed.
So I purchased a 12 point 2" socket made by Stanley on eBay for $21.50 shipped. I verified it fit as I could easily push down on the strut piston. The 3/4" drive opening was already close to being big enough. After about 30 minutes of enlarging the hole using my "worth its weight in gold" Makita rotary tool, it would now slip over the piston. Next was to grind some flats on the socket so I could use a pipe wrench to turn it. Threw it on and with one good turn, the glad nut was loose! Once I off I verified there was no damage to the strut tube or the gland nut itself. You can see in the last picture with the gland nut in the socket that the corners are not exactly aligned in to the socket. I am a little lucky as the entire suspension on my car was rebuilt in the past few years. Why the strut insert has already failed on stock springs is another story. If your gland nut is really stuck there is a decent chance the socket would slip. Going down one size may help with this. Anyway, that was my solution, it worked, and thought I would share.