In a few spots these old Mopars use fittings with bigger threads and a bigger hex, but the flare/line size inside is the same as all the other lines. I guess it was an "idiot proofing" thing to avoid having some of the lines mis-assembled.
Yea i ran into this problem last time, I think I used a 1/4 in adapter but I believe the correct size fitting is a 5/16 standard inverted flare fitting. I'll go grab some fittings tomorrow and try them out, the ones that work will make this brake line job complete.... unless I change out those rear wheel cylinders.
