Ford 4000 Hydraulics

Thanks everyone. the pictures make it look nice & clean & easy
From what I read from Dieseldogs post & others that i'm reserching I have just changed the transmission oil which has nothing to do with the hydraulics : :-[ :-*
I have found the fill point for the rear end which I'm presuming is also the hydraulic side as that's also the hydraulic return, but looking & looking even my seeing eye dog cannot find a drain plug under what I would call the DIFF. If I do find one or get the milky slushy type oil out by other means How much nice clean oily substance do I put in?
Cro

Cro, from memory The drain plug for rsend is hidden by the Drawbar

According to here; www.tractordata.com/farm-tractors/003/7/7/3771-ford-4000.html

31 litres....