Maybe everyone here already knows this, but last week when I was replacing brake lines on my 71 I found that Carquest has 8" pieces of 3/16 line with a 3/16 tube nut on one end and a 1/4 or 5/16 tube nut on the other. When I was building new front lines, before flaring the ends I put new 1/4 tube nuts on the ends that joins with the brake hose. Would also work from the master cylinder to proportioning valve or any place where you need a larger nut for 3/16 line. 3/16-1/4 part number is 318A, 3/16-5/16 is 328A. They also have several other configurations. I got them just for the tube nuts, the old ones were permanently fused to the lines, and had been vise-gripped off in the past. My brake lines are now new end to end. Hope this might help someone out.
