I've located 4" tapered lift blocks for my truck and I'm not sure if the centering pin is 9/16" or 5/8" does anyone know?

 

5/8...almost every ford from the ranger up to the f350 uses a 7/16 centerbolt which has a 5/8 head on it. Chevy uses 3/8 centerbolt with a 9/16 head on it for everything up to the one ton. Dodge is all over the place using 3/8 all the way up to 1/2.