I need someones help desperately.
I have a 2006 F250 - the main brake line that comes from the ABS Relay to the rear, along the driver side split. no one seems to know how to fix this, not a single mechanic, they keep calling me and asking me what size the fitting is that comes out of the ABS modulator.
can anyone help me, please.....I am desperate at this point.

 

There are a few avenues you can choose.
You could call your local Ford Dealership Parts Dept , provide you're VIN and they should be able to tell you what size Metric thread is used there. They may even be able to help you with the correct tubing to replace the defective part..
If you have other means of transportation, you could take both ends and the line with you to a local auto supply store and they might be able to match what you have removed.
Some places will deliver if you cannot get there , you need to ask. There are reasons why we try to deal locally for situations like this . Some stores that know you and deliver will usually try to help you out.
I guess you might try to purchase on line, but If you get the correct parts, great , if not the lower price may not be worth the trouble if you get the wrong parts.

 

What it the actual problem, I assume its that you need a new hard brake line but you didnt actually say that.
NAPA I know will make you new hardbrake lines to match yours but I believe you have to bring in what you want replaced for them to match it.
It might be easiest to just buy a new hard brake line from the dealer.