spring perch nut size?

I am on the way to Tacoma screw for some nuts and bolts and want to pickup some Nylock nuts for my spring perches on a traditional Ford setup while i am there, anyone know what size the are?

 

You refeing to the spring U bolts ? As I recall 1/2X20.

 

I think he is talking about the buggy spring perch the connects the bones to the axle. They are bigger than 1/2 and they are fine thread. Im interested as well, would feel better with nylocks.