Mjic X Male Din 2353L (Sealed)

That's what this one's built for. One end is a JIC male at 7/16-20 UNF and the other is a DIN tube male at M14 x 1.5, so it bridges that metric-to-37-flare connection without any extra hardware. It's a straight adapter, steel construction, and the DIN side carries the 2353L sealed designation, so you're not relying on thread sealant to keep things tight. At 33.3mm long and 19mm across the wrench flats, it's compact enough to fit in tighter hydraulic connections runs without much fuss.

Designed for secure connections in industrial applications, this Adaptall fitting is made from steel, so it should be durable enough for log splitter hydraulics, assuming the pressure and fluid are compatible with steel.