Nut, bolt and screw sizes

[Mr Spigot]

While searching to find out the size of the bolts on the exhaust manifold flange on my MM, I found a part number in the parts manual FB106/11. With no further details I did an online search and discovered a list of nut, bolt and screw sizes for a Jowett, although the part number above came up, with a load of other sizes as well as an explanation of the parts numbering system. From this I learned that FB was: F = British Standard Fine (BSF) Thread, B = Bolt, with Shank, 1 = Hexagonal Head, 06 = Bolt Diameter, 6/16" (or 3/8") and 11 = Length of bolt from under head to end of thread (Multiples of 1/8").

It occurs to me that this would be a very useful resource when trying to replace nuts, bolts, screws etc if unsure of the exact size, as this field can be very difficult to comprehend if not an experienced mechanic or engineer.
I hope this is of use!

https://jowett.net/Parts/TechNotes-Part23-Hardware.htm