the thickness varies from the middle to the edges of the leaf,
and the width of the leaf is wider at the ends than it is in the middle.
also the leaf isnt bolted to the others in the middle, there is more leaf forward of the axle or vice versa (cant remember which)

if you like i can do a bit of a drawing for you with some more accurate measurements
but i do have spares here in melbourne if its easier for you than getting some made?