Tower and bones

[bald eagle]

I broke a rear wishbone on my x6 the other night. I have been advised that if I get another pair of wishbones to replace the one I broke, they are "handed", so if i go and break the same side again, I will have to buy another pair of wishbones. I want to know has anyone tried the squared tower and wishbones on their old version x6? Will I only need the tower and wishbones or other bits? What is the reason for having to buy the tower?? will the gometery be different?