Grade 2 is a standard sheer bolt but will break under a small load. I use a grade 5 bolt with my mowers and they work a lot better, don't have to change them after hitting a gopher mound. Do NOT us grade 8 bolts, they will not break and cause a lot of damage to your mower.
Jeremy
I have a 60" general busghog was wondering what is the best grade of bolt to use. currenly using grade 2