That's the point. I don't mind different steel or wire diameter, but different shape?
This is my old springs:
And this is my new ones:
The lower part is cylindrical and the wire doesn't fit intended groove (or whatever it is called) in the rubber insulator and in the strut itself.
Ok, in fact I've already installed the springs. After initial shock
I turned on my brains and found a solution. Looking at struts I always wondered why they have three holes in the spring support plate. For some kind of spring retainers? Never seen anything like that, but in my case I really needed something to prevent the spring from sliding around. So I just bolted M8x1" bolts in those holes and drilled the rubber insulator so it can lay flat in its place. Now the springs kinda rest on those bolts and I've been able to assemble the struts with acceptable degree of certainty.
Looks like it will work Ok, but I'm not happy with this solution. No way GM designed it to be mounted like that, but I can't see how it can be done differently.