[mgrover]

The dealer said the front and rear are rusted, video of them https://video.citnow.com/vxy4ChjbYTJ if anyone fancies it

What are these? And how bad is it a DIY to replace them? And where would I get the parts from? Everywhere I look their atleast a £1000.

 

[rayodunne]

You could pull the lines and bring them to a hydraulics shop. Any agricultural supply place should be able to point you in the direction of one. I had a line built for a Disco 2 with active swaybars years ago.
You might be able to grab the regular sway bars from junk yard and disable the active sway control or whatever it is called on the RRS. Again, might be able!

 

[mgrover]

Why can't I just get the sway bars and stick them on?

 

[rayodunne]

Mechanically I can't see any reason for it not being possible. You would need the sway bars, swaybar links and sway bar bushes. You would also need to put a shorter serpentine belt on bypassing the ACE pump.
Electronically, I have no idea! Somebody else might help you.