ugh lol im confused... what I was meaning is use the plastic reservoir and bore out the hole a tad and then put a metal fitting that is threaded and tighten that sucker down!
this is basically what is in there OE... the black one only NOT threaded its just popped in there like a button works

and what i was meaning is taking a fitting like THIS

and put a nut on the back side (inside the reservoir) and tighten the hell out of it! Im pretty sure that would finalize the deal!
but anyhow DEAD HORSE... I ordered the new reservoir today