First question: If you want to use it on US Cellular, why does it have to be unlocked? (Unlocked only means that - with some phones - you can use it on other carriers.)
Second question: Which other carrier are you planning to use it on? If it's not a CDMA carrier, it won't work. If it's Verizon or Sprint, the only other CDMA carriers in the US, they won't accept it on their networks.
Just look for the SM-960U (that's the US cellular version). The chances are that, with a CDMA phone, it's not SIM-locked to begin with. (Most of them aren't - Verizon hasn't locked its phones in a few years. The networks "lock" the phones by just not letting them on their networks - you have to buy their phone to use their network.)