Confirming Nut Size

Finally beginning the tear down of the engine of my 1975 850 Commando. What size are the cylinder head nuts identified as retainers 7&8 in the shop manual for tightening and item 18 on the Andover Norton Parts listhttp://www.oldbritts.com/1975_g2.html?

The other nuts, bolts for the head are 1/4 W, but retainers 7&8 seem smaller.

Thanks,

Jim

The late sleeve nut hexagon size is: 7/16" AF.

Thanks