Franklin, The lines we have are 3/16" lines. You obviously know that, since you said so. 
The line size inside the flare fittings is just as important as the size of the fitting itself.
If the fitting is for a 1/4" or 3/8" or larger line, the connection will leak, because the smaller line will never seal.
I couldn't find the line size on any of those fittings.
The first fitting only says 3/16". No idea whether that is the line size or the flare size. They don't say anywhere. I asked the question there. We'll see if anyone answers.
But here is a "kit" that includes 8 line nuts that are 3/8 - 24. And 4 connectors that will connect them together. All of them in 3/16" line size.
connectors
That will give you your connector, with three extras, and some line nuts. If you can do an inverted flare, just cut the line that has the 1/2 flare nut on it, and put one of the 3/8 flare nuts on it. Yer done. Just connect it straight through. All for less than 9 bucks.
I CAN say that the last fitting is a 3/8 - 24 FEMALE, to a 1/2 - 20 MALE.
If you want to connect our lines without cutting out that 1/2 flare nut, adding the 3/8 flare nut, and re-flaring the line... it would have to be the opposite.
To use that type of fitting, you would need a 1/2 -20 FEMALE inverted flare, to 3/8 - 24 MALE inverted flare, with a line size of 3/16".
This is the only thing I have found on amazon that even comes close.
adapter fitting
It says 1/2 od for the female side. And 3/8 -25 for the male fitting side.
Now at least it says inverted flare. And if you look inside the 1/2 female side it indeed looks like inverted flare on the inside. But the male side does not look like inverted flare.
Plus, it LOOKS like it is a lot larger line size than 3/16". I asked them what the line size was.
Even if it is 3/16" line size, now you are going to have to find an adaptor from the 3/8 NPT male end, to the 3/8 -24 inverted flare connector you have.
Easier to just cut the 1/2 nut off the line and replace it with a 3/8 nut.
~~~~~~~
But again, none of this is what this thread was about.
I was just making the suggestion that, instead of going through all that searching for the exact right fittings... The only thing you need to buy is a 1/8 npt pipe plug.
Remove your RABS valve. Tap the hole, (FOR 1/8 npt pipe plug thread.), where I have shown. Insert the pipe plug. (With hydraulic sealant.) And put everything back together.
Done. And everything looks just the same as when you started.
The line size inside the flare fittings is just as important as the size of the fitting itself.
If the fitting is for a 1/4" or 3/8" or larger line, the connection will leak, because the smaller line will never seal.
I couldn't find the line size on any of those fittings.
The first fitting only says 3/16". No idea whether that is the line size or the flare size. They don't say anywhere. I asked the question there. We'll see if anyone answers.
But here is a "kit" that includes 8 line nuts that are 3/8 - 24. And 4 connectors that will connect them together. All of them in 3/16" line size.
connectors
That will give you your connector, with three extras, and some line nuts. If you can do an inverted flare, just cut the line that has the 1/2 flare nut on it, and put one of the 3/8 flare nuts on it. Yer done. Just connect it straight through. All for less than 9 bucks.
I CAN say that the last fitting is a 3/8 - 24 FEMALE, to a 1/2 - 20 MALE.
If you want to connect our lines without cutting out that 1/2 flare nut, adding the 3/8 flare nut, and re-flaring the line... it would have to be the opposite.
To use that type of fitting, you would need a 1/2 -20 FEMALE inverted flare, to 3/8 - 24 MALE inverted flare, with a line size of 3/16".
This is the only thing I have found on amazon that even comes close.
adapter fitting
It says 1/2 od for the female side. And 3/8 -25 for the male fitting side.
Now at least it says inverted flare. And if you look inside the 1/2 female side it indeed looks like inverted flare on the inside. But the male side does not look like inverted flare.
Plus, it LOOKS like it is a lot larger line size than 3/16". I asked them what the line size was.
Even if it is 3/16" line size, now you are going to have to find an adaptor from the 3/8 NPT male end, to the 3/8 -24 inverted flare connector you have.
Easier to just cut the 1/2 nut off the line and replace it with a 3/8 nut.
~~~~~~~
But again, none of this is what this thread was about.
I was just making the suggestion that, instead of going through all that searching for the exact right fittings... The only thing you need to buy is a 1/8 npt pipe plug.
Remove your RABS valve. Tap the hole, (FOR 1/8 npt pipe plug thread.), where I have shown. Insert the pipe plug. (With hydraulic sealant.) And put everything back together.
Done. And everything looks just the same as when you started.
