I agree, the later harness (package) would be most likely to include the additional wiring required for connection of the front brake switch, although it was still not built in to the main harness.
There is also a revised 'Body earth wire' (battery to frame/rectifier) listed, part No. 8831-9010 for (I assume) machines with the front brake switch. I can only guess this was made slightly longer than the original part 8831-9000 to facilitate battery disconnection. It was not required to allow fitting of the front brake switch. Maybe a later small improvement to the wiring system.
Brian.