2004 Silverado brake line wrench size
 

Hello I had the rear brake line rust out and burst and I can’t figure out what size wrench to use to get the brake line out of the abs box. I’ve tried 12, 13, 14 and 15mm seems like it’s between the 14 and 15. I’ve also tried 1/2, 9/16, 5/8 and it seems like it’s between the 9/16 and 5/8. I’ve tried Crow foot wrenches, line wrenches and normal wrenches and I can’t get any to fit. Not sure if one of the ones I mentioned fit and with the zero room you have where the abs box is to work on these things I’m just not getting it on correctly or what. Any help or direction to go would be awesome I’ve been trying since yesterday morning to get this out and can’t seem to get it. Or if there is something to do to make it easier to reach the fitting I thought about taking all the lines out but I’d probably have just as hard of time and end up having to replace them all if I go that route! Help please!!!!!
https://cimg1.ibsrv.net/gimg/chevrol...f013d313e.jpeg

since you are replacing the brake line...cut the line at the compression nut and turn it out with a ratchet. if you do them all draw a diagram to help remember which wheel or master they go to

Yea I cut off the brake line and have been trying to get a socket on it but I can’t find the one that fits all of them I tried are just too small or just too big. Tried 14 and 15mm too small and then too big tried 1/2, 9/16 and 5/8 too small too small too big. They all could be replaced from the rust shown in the picture above but I was really hoping I could just do this rear one today and the rest later if possible. Seems like I’m going to have to cut them all and take the entire abs box out and get them all out afterwards and replace all the lines at this rate.

due to the rust you probably have to hammer the socket on

The question still remains "what size socket should be hammered on?" I am currently having the same problem.

Wrench size is 14/15

That is not a wrench size.

Most times the lines and nuts are different sizes.
I believe the 14, 15 was referring to Metric sizes.

Also you might do a little homework on the required bleeding procedure, that will require a scan tool capable of operating the solenoids to get all the air out of the system.
Otherwise you will never be able to get a solid pedal.

Thank you for giving the first clear answer to the question. I will be taking it in to a trusted mechanic to have it bled properly. I just need to have some kind of stopping ability to get it there. I just needed to know if it is a 14mm or a 9/16 which is 14.3mm

Update and the fix
 

Ok here is an update for what I used to handle this problem. I used PB Blaster on the flare nuts, then I cut the line. I used a 14mm socket and hammered it onto the nut until it was flush with the abs module(or whatever the technical name for it is). Then it was easy to remove the nut using a ratchet. Now I can replace the line and have it bled by someone with the proper tool. Good luck to all that need this information.