What size and grade of nuts and bolts for attaching smooth edge to bucket?

[pgmrdan]

I need to attach a smooth edge to my skid steer bucket.
Someone mentioned using two nuts for each bolt so the threads are protected. The old nuts and bolts were cut off with a torch before I got the edge.

Thanks.

 

[Impact-vector]

I've never had an issue with grade 8 and nyloc nuts. Use washers as needed

 

[brdgbldr]

I've never had an issue with grade 8 and nyloc nuts. Use washers as needed

Most smooth edges use plow bolts. The edge will have square openings and recesse to accommodate the plow bolts. Just make sure you get the proper length bolts so you don't have to cut them off after tightening them.