Power Steering Parts for 1966 Dart 6 cyl
The return hose should be all one size - 5/8th to match the pump and the box. So it’s possible the pump has been replaced in the past with one with a 3/8in hose return port. Check with Steer and Gear as I sent them a correct slant pump with the 5/8th port as a credit trade-in when I had them rebuild my V8 pump with the 5/8th port