58mm backspring question

[ComboTool]

Hi, I'm planning to do a Victorinox 58mm mod. I've taken apart a few knives and I've encountered two kinds of backsprings (besides the presence/absence of keyring attachment). One kind seems to be strongly interlocking (top pair), the other less so (bottom pair). Besides the fact that they don't seem compatible with each other, should one be preferred over the other? Is one more recent, maybe less prone to snapping (a common problem in the old 58mm I have gathered)?

[ComboTool]

I've now found a third version. This one (the bottom pair in the picture) I think is quite ancient (at least it doesn't come from a current model). Does anyone know if there are others, when the changes were made and why?