I bought a one way bleed screw and started to fit it on an extension, but then decided to replace the entire diff with a Jag one.
Someone does make a kit for the Jag diff which is where I got the idea.
All I was going to do is to remove the bleed screw, fit a suitable size flexible hose instead, then run the hose to a bracket somewhere a lot more accessible perhaps even inside the boot somewhere safe, then a double ended adapter with the one way bleed screw.