what is used? and how much, ive got a tran x diff in there

GL-5 Hypoid Gear oil (I think!). Available from Halfrauds. Mine took just over 1l (which meant a 2nd bottle!).

75-90 grade? where do you fill it to, up to the allen key thing?

any one? need to fill it tonight and im unsure thats all, ta

Not sure if I'm talking goolies or what but I think you fill it up until it comes out of the filler.

JB