..."I found them odd tubing nuts for the crossover tubes on our brakes. They are 1/4" with a 20 thread pitch normal 1/4" tube nuts are 24 pitch anyway the only place that has them around here is Williams’ Oil Filter in Tacoma."...
I also have/can offer most sizes of tube nuts in stainless steel.
Here's a thread about them , and copper nickel brake line as well.
Grigg