One thing it positively is NOT, and that is an Arizona Mountain kingsnake(L.p.pyromelana). I see some milksnake characteristics in the animal, but it doesn't look like any particular milk subspecies either.
It looks to be a cross of somesort. But it is virtually impossible to say exactly what.
This is a pic of an Arizona Mountain king.
~Doug

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"a snake in the grass is a GOOD thing" 
my website -serpentinespecialties.webs.com

