Body mount bushing bolt size?

I need new bolts & noticed @Ryan_3TacosIn had put 15mm in his how to post. I have 17mm. Two of the stock at position 3 & the others are not stock. They were replaced by the mechanic that screwed them up a couple of years ago. I am unsure as to whether he bought new position 3 & may have got the incorrect size. I have the same energy suspension kit ryan_3Tacosin used, so should it be 15 or 17 or does it matter? I can’t find any guide in the manual or online. So what I meant was bolt head size, which I imagine makes the dif between using an 8 or a 10, yes?