fitting steering box, tips ?

Fitting steering box on disco tomorro, any tips before i go ripping it off ?
How much oil will i need ?

Disco 1 or 2?

Not done a disco one but have done a few rangies and one thing I learnt after the first one was to get the box up and get the threaded unions of the pipes started first.I found that it was easy to do it this way as the box is not held rigid so have some flexability then when you have them about half way in bolt the box back down to the chassis.The first time I got the box partialy bolted down and could not get one of the threads of the pipe union to start and after much swearing and trying I took the box off and did it that way so much easier.

Disco 1