Lower Ball joint bolts

Hi all, i have something i have not seen before when working on b bodies. The lower ball joint bolts on this Barracuda i'm working on has 1/2 x 2 7/8 long NF nut and bolt install. i;m used to seeing a castled nut and cotter key. So my question is which is correct, the nut bolt and cooter pin or nut and bolt only?

Also the aft or rear bolt has a round head on it meaning it is not flat.

Thanks