It is a bit of a PITA if you mess up that fitting. The fitting is part of the brake line and normally is sold with a section of brake line.

The problem is that you need to connect this new brake line, with fitting, to the existing system. This will require a double flared end with a suitable fitting for the connection to the existing line. The existing line will also need one of the same fittings and a double flare.

I have not purchased the tool to do a double flare, and have replaced the entire line on the Dodge van when the same thing occurred. I'm not sure how difficult this will be on a M/B.