A body structure has an inlet port that receives fluid, a first outlet port that connects to a top-fill line of a cryogenic tank, a second outlet port that connects to a bottom-fill line of a cryogenic tank and a slider tube cylinder. A cylinder housing connects to the body structure and has a pressure comparison cylinder with upper and lower volumes, with the latter in fluid communication with a cryogenic tank. A piston having a piston shaft slides within the pressure comparison cylinder. A pressure regulator is in fluid communication with the upper volume and the slider tube cylinder. A slider tube is connected to the piston shaft and slides within the slider tube cylinder. The slider tube cylinder selectively directs fluid to a top-fill line through the first outlet port or to a bottom-fill line through the second outlet port.