This is interesting and solves a little mystery
I'm building up my gearbox and as it has been some weeks since I was last at it, I chose to check the gear positions/ no of teeth against the part book.
The problem came when I got to the first gear on the Layshaft ( 1st gear - nearest the kickstart ?) part number on the parts book diagram is 67-3199, this number is not listed amongst the parts descriptions though and in fact it probably should be part number 42-3097 as in the chart above .
So thanks for that
All the best - Bill