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The last time I messed with one, they were different sizes. They were either 5/8" and 3/4" or 1/2 and 5/8. Can't remember which. The point being, you can't get them wrong unless you really work at it. Good luck.
Not sure if it matters or not. On mine (390) The uppers inlet on the heater core goes to the intake, and the lower inlet goes to the water pump. Both my hoses are the same size, Im pretty sure.