i bought a receiver hitch off a guy and it came with 4 bolts and a plate that the bolt screw into for the top side. does both sets of hole have this plate or can i just use some bolts with washers? i bought grade 8 1/2" bolts with grade 8 nuts, and grade 8 washers. will these be ok? and should i use lock washers?

 

if your not gonna go the lockwasher route take and tighen the bolts tight and put a punch at the threads where they come out of the nut and smack 2 spots on each bolt to help prevent
the nuts from coming lose

 

Grade 8 bolts are good for this. If not lock washers, use lock nuts.