C5 Master Cylinder Tube Nuts
 

One last piece of the puzzle for my brake install is tube nuts for the C5 master cylinder.

It appears that the front port is M12 x 1.0, and the rear is M12 x 1.5. The issue I'm having is that I can't find anyone who can supply the M12 x 1.5 tube nut for use on a 3/16 line.

I've seen people mention they were able to find M12 x 1.5 fittings for 3/16 tube, however I have yet to come across a thread which provides part numbers or where they were sourced from.
Does anyone have any guesses to where I could source them?

Baring any breakthroughs there:
I have the stock fittings. The rear port originally used a 6mm tube. The difference between 6mm (.236) and 3/16 (.187) is a hare under .005
While that seems like a relatively small difference, I don't want to do anything to jeopardize my safety on a critical system such as brakes. Could the original nut be reused for the 3/16 lines? Another option I'm considering is using 6mm line from the rear port into my proportioning valve.

.049" is a lot, I wouldn't use the factory nut on a 3/16' line.

Is this the flare nut you are looking for?

BQ9193 M12 × 1.5 11.6mm 45° 13mm 3/16″

from http://brakequip.com/products/hardware/male-tube-nuts/

Yep, that's exactly it. Thank you. I could have swore I checked them, but obviously missed it.

It also appears they have a distributor within a few miles of here.

Not sure if these adapters would work for you or not but it is what I am using. https://www.summitracing.com/parts/aaf-all41012