Upper strut mount replacement Q

[Smytty]

I recently replaced my upper strut mounts and bearings. When I pulled them apart, the cross shaped nut was installed upside down on one of the sides _ it had been done at a local shop a few years ago. (i.e. the flat part of the nut was up on one side, and down on the other side.)

So which way is the correct way? On the nut itself, the side with the cross is flat, and there is a small radius to a round portion on the other side. (Sorry, I don't have a photo handy) Does the flat part go up against the bump stop, or down close to the upper spring seat?

On any of the exploded diagrams I've seen, there isn't enough detail to tell which way is up so to speak. Normally, I'd just replace them the way I found them, but now I'm not sure which one is correct.

Any help would be appreciated.