Lower Front Shock Bolts

The comment on using a lock washer here is not ideal IMO. Use a typical nylon style lock nut or ideally an all metal "stover" lock nut with a grade 8 bolt. NF or NC by itself is again IMO not critical here as long as threads are not part of the shear loads.
I have been amazed how the local Ace Hardware has stepped up their fastener selection in recent past years, likely to stove off, pun intended, encroachment by a big box like Home Depot.