As you can see in the group picture, the two bolts easily screw into both types of nuts. These are left over from the renovation of a Triton horse trailer. These are all new. The numbers below correspond to those added to the pictures.
#1-- Nut with six sided star head. 5/16" -- 18 x ½". 8 nuts for $8.
#2--Nut with the three notches. 5/16" -- 18 x 2". 51 nuts for $17.
#3--Bolt threaded all the way from end to end and button head along with a corresponding neoprene bonded washer. Bolt is 5/16" -- 18 x 2". Washer is 5/16" x ¾". 9 bolts and washers for $5.
#4--Bolt partially threaded step bolt. 5/16" -- 18 x 2". 23 bolts for $6.