To determine which motor has a fluid flow of 340 GPM, we would typically need the specific flow measurements from each motor's gauge readings. Since that information is not provided in your question, I cannot identify which motor corresponds to a flow of 340 GPM.
If you have data from the gauges (e.g., flow rates for Motor #1, Motor #2, Motor #3, and Motor #4), please share those details, and I would be happy to help you identify the correct motor.