I see it seems like a thin wrench is needed, and that hose crimp won't let you slip a line wrench on.
If it were mine, I'd wrap the hose ends in wet rags and hit the brass Tee with a pencil point plumbing (acetylene) torch .
Hot and fast as I could get it to smoking.
You can cool it off at that point because once the polymer is broken it's never going back to what it was.
Again, this seems like an excellent application for PST, and the lubricity of Teflon on the threads is never a bad thing.
If it's zinc in brass you probably want to use primer.after you clean the old stuff off/out with a wire brush and acetone.
Jim,
Lil'Red is a '87 F250 HD, 4.10's, 1356 4x4, Zf-5, 3G, PMGR, Saginaw PS, desmogged with a Holley 80508 and Performer intake.
Too much other stuff to mention.