Not sure about a CB6000 with the kubota depends if its lpg or diesel but the the cb6000s with the toyota 4y have the starter located on the back side of the engine (far side when looking at it with the hood open) and theyre easier to get if you remove the rear wheel and go up from there.

I think the kubota lpg is the same but the diesel kubota starter are located on the opposite but i cant remember