[One Outer]

It widens opponents c/r range to me. Villain could have been leading any pair or a straight draw into you and now he's picked up a bunch of extra outs. Villains play is how I would play 87s, 43s or a pair against some opponents if I picked up a flush draw on the turn. Not that I'd call 34 pf but that's neither here nor there.

If the K doesn't put out an additional draw out I think I'm revising my original answer. What hands could villain reasonably c/r here? I think the range question is kind of esoteric because this is a blind steal situation. It's much harder to pin down a reasonable range, imo.

If we're believing villain's story here and the K doesn't put out a flush draw I have a hard time putting him on a hand that doesn't have us beat here unless he would do this with just a Q or K. The question is then what hand does he b/c the flop with that contains no pair and a K? Nothing reasonable, I guess. I think KQ would have threeballed preflop and/or on the flop. The only logical hands that beat us are are K5, K6 and then there are the unlikely combos of 55, 66, KK or QQ (I'm discounting the big pairs very, very, VERY much). To me, that means the majority of the time villain's range has picked up outs here and is semi-bluffing us. That makes it an easy threebang. All of this is predicated on the turn putting out two of a suit.

Of course, if the turn completes the rainbow villain's story is much more likely to be straightforward and I'm calling down barring improvement.