Mick,
You will need to put SAE30 in the gearbox, and EP90 in the transfer box. If I remember correctly Richard F mentioned that a few ferrets took the same oil in both, but I'm fairly sure yours will be the same as mine. You could try flusing out the gearbox, I'm not sure what kind of cleaner would be suitable though. If I were you I'd drain it, fill it with fresh oil, run it for a few miles and then change the oil again. Hopefully that will get rid of any nasty old oil.
Chris