Help K member bolt size

I would really appreciate if you could. If i can't find a local source then I'll order from ebay (had bad luck with ebay)

ONCE U GET THE SIZE FIGURED OUT , u can go to fastenall and get allen head bolts the same size , of course you`ll have to use dthick washers w/ them . I have had 2 on my car now for about 10 yrs . .