Sorry I can't help you but you should be able to google the manufacture of the wet bolt system to find the size.
I do have a question for you. How often do you grease your bolts?
I have had the wet bolt system on my trailer since new, bought new in May of 2015. This unit has over 20,000 miles on my trailer and I have never lost a bolt. They do get greased every 4,000 to 5,000 miles and inspected every time we pull the trailer.
2016 34RL CC; 2008 Ram Mega Cab 2500HD, 6.7L, 68RFE 6 speed, 4X4, Smarty S67, TDR 135K+miles