77 4x2 steering box inlet/outlet thread and sizes?
 

Hey all. I'm doing a hydroboost steering conversion on my 68 C10.
I've installed a power steering box from a 77 c10.
I bought -6 AN stainless power steering hose and hose ends.
Everything has appeared to go together well, except the outlet port on the steering box.
I purchased a 5/8-18 in. Male Inverted Flare, 90 Dergree, Swivel hose end from summit, but it appears I've got something wrong.
Even after tightening the fitting, it still has movement in it.
See video link.

Did I install the wrong fitting for this box?
If so, what's the correct thread and size of the port on the box?
Thanks!
http://youtu.be/rdGJ1PY9Jwk