Rear brake line?

[Keasbey]

The flexible brake line that goes to the differential is shot, and it seems that I can't remove it from the piece of metal that retains it.

Is there a special way to remove it?

 

[rd]

It should be a simple threaded fitting. It may be original and crusty.

Spray some penetrating oil on it and it should thread out.
The axle end should be the easier of the two to remove, in my experince.

If you have the new line, you can cut the old on next to the fitting, and put a socket on it.

I would start with tube wrenches, but vice grips will probably be necessary . As a last resort, take the hard lines off at the wheel cylinders, and the whole thing comes out of the car. Then you can carefull get the old fitting out of the junction block so you can reuse it.