Diff and boxes oil change.

So the rear diff filler plug was .....stuck , but I bought a draper 10mm square gearbox key ( 8mm) the opposite end with a 17mm 3/8 socket fitted ...good tight fit and easily undid..as did the drain plug. Repeated at the front.
But the transfer box is a larger size , do we know what size it is?

Also the gearbox filler.....where is it The drain is obvious I read somewhere it is on the left just above the drain , will look again tomorrow.
Am I in the right area..?

I think the gearbox filler is the same size like the drain plug. 10mm if I'm right.

Cheers found the little bugger, (gearbox filler ) who put it there?
However following the info that they are the same size ...logically , I used the calipers to check the size of the transfer box drain and filler , and gearbox drain ......bugger a unique size of 11. Summat mm....obviously the previous keeper adapted a tool to mash them open ( the plus side they must have been done, it had just had new transfer box mounts before I bought it!)
On the plus side the gearbox filler came undone with the 10mm diff and a ring spanner! No scaffold tubes needed.