You mean the big bolt that goes through the eye?
If I'm not mistaken it asked to be a certain length and size.
As in I'm not sure if you can just buy one off the shelf? I'll be curious to see...
Oh yea, you can.
I got the grade 8 fine thread type with the nylock nut, but I did have to get a long shouldered bolt and cut it down at the threaded end so it had the smooth shank all the way through with an inch or so of threads left at the end.