Stab in the dark at Black for ground, plus yellow/black
I don't have a manual for it, an 1860 may be similar,
http://www.kubotabooks.com/AutoIndex/index.php?dir=Tractor%20Owners%20Manuals/&file=BX1860%20BX2360%20BX2660.pdf
but best if you can get the correct one if it's available. Send North...