I have a 99 F150. I just replaced the two lines from master cylinder to ABS unit due to being rusted through. Went to use the brakes and blew out the line going to the rear brakes. However, when I looked under neath it the next day to fix i noticed that the main line going to the rear brakes was missing a section of it right after it comes down from the ABS unit. Is there another T block or something that the line runs from the abs unit to before it goes to the rear brakes? Need to get this truck on the road ASAP. Thanks for the help in advance

 

When my '99 rear line went I toke it to shop. They went from port on abs unit outside the frame in a tidy manner. Then thru a hole in frame and behind gas tank to junction with rear rubber hose. They did not follow org path as that would have been much more time.
Org. path was from abs port over the top of unit and under to the rear. It was two piece line with coupler block in the middle. Two off the shelf pre-made lines with coupler in middle. It has adapter between abs port and brake line threaded nut.
The rear line was not connected to any other line or part.