rear brakes won't bleed

I did read an older post on this but still a little unclear on my problem. I did a front disc conversion, have all new lines, master cyclinder, proportioning valve, t -block ect. I get a good stream out of the front but little at the rear, there is fluid. I did break the line loose at the rubber hose before the t-block and got some fluid there but not a strong stream. I did read something about resetting the proportioning valve but not positive on what to break loose on it to do this. I know that you should hear a click when it resets, so could someone post a picture of the fitting that needs to be broke loose. This is for a 72 dart. Thanks for any help it will be deeply appreciated.