I would raise here. A three is dead and it is likely a 5 is dead also, since the better looks to have a straight and can only do so with another 5. If you raise you will get called by the 5 seat and also the 4 seat. I just don't think he is full, and if you agree with that, the best choice is to maximize your win with a raise on 6th. That's is at least what I would do here. And they will both call you to the river. Hopefully the 4 seat won't fill up with his hidden pair.