Rear brake line

[M. C. Gilly]

I’m replacing the brake lines in the rear. There is what looks like a splitter but appears more elaborate than anything I’ve seen before. Can anyone tell me what this is and, if it isn’ta simple splitter, how it functions?

Thank you for any information you can provide. 
 

[rogold]

Here is another one Rear Brake Proportioning Valve 1988-1990 – East Coast Reatta Parts

[2seater]

It looks to be the rear proportioner valve, but internally it looks to function as a tee. When I do rear brake lines, I replace all the steel lines but first I relocate that proportioner to the center front face of the rear crossmember. Clamp in place with a steel single bolt tube clamp. You can eliminate that flex line if desired as well. It makes routing new lines so much easier. Even though the proportioner may look crusty on the outside i have yet to find one that isn't pristine on the inside. Clamp the thing in a vice and remove the rusted tube fittings with the vice grip or small pipe wrench if necessary. Assume all rear steel lines will need replacement up to the area where they cross to the outside of the "frame"