It looks like both kingpin bolts were made out of existing hex head bolts. The top kingpin has a 15/16″ hex and is drilled for safety wire. None was installed. The shoulder is only a few thousandths longer than the bushing. I found this can create the problem of the bolts backing out during use. I thought the top bolt was drilled and tapped for a grease fitting. Turns out it was only center drilled. The bottom bolt has a 7/8″ hex and the shoulder is about 1/32″ longer than the bushing. The threads come up about 1/4″ short of the shoulder so the kingpin jams on the 1/2-20 UNF threads instead of locking up on the shoulder of the bolt. The threads are about 1/4″ longer than the top bolts threads.
The top bolt is on the left, the bottom is in the middle and one of my oversize thread bolts is on the left. I am going to have to use an oversize bolt in the bottom because the fishmouth is cross threaded at least twice, maybe 3 times. Ughhhh