it's either m12 or m14 bolts....thread pitch, i'm unsure. If you've got a box of stock bolts, it'll be the ones that approx 1/2" in diameter and approx 1.5-2" in length.
Hope I helped.
*IDK if those 98-00 hooks take the same bolts, I'm speaking about 01+ hoooks.
Here's a hook with all the bolts...