Mitsubishi BD2G

Hi,my first post here and most likely not my last. I have just purchased a Mitsubishi bd2g dozer,my question is,when you lift the seat up,you can see the 2 little rams that the steering levers move too turn the dozer..
There is a dipstick there too check the oil,can someone confirm with me what oil grade should be used in here,as it is very low,also what part of the dozer is this called,is it the transfer/bever case ????.
I'm from Australia and any help would be appreciated...
Regards Swimmer...

Mitsubishi BD2G