final analysis: joe gets the girl.
at the end, joe has his gold in the old beat-up pickup truck. the pipes he was painting are fake-- but who knows, maybe a few were real to pass closer inspection.
just before they drive off with the fake gold, there's an odd conversation between joe and fran, where she says "cute plan, though--" and joe looks at her as if this is an odd thing to say. his expression is: "yeah, cute as a chinese baby."
here the camera cuts back to fran, who gives a nod.
this to me indicates that another codephrase, similar to "pristine," used by pinky, was used to communicate that he has the gold, so fran should could back.
the fact that the exchange even took place, with the codequestion/codephrase query/response leads me to believe that they've been working together long enough to be partners for life, criminally and matrimonially-- if they are indeed married.