Power steering valve body

Hi guys. I finished replaceing my power steering gearbox and pump on my 73 duster. After dealing with the headaches from oreily auto parts. They gave me a gear box the has striped splines on the input shaft. It took me forever to make the guy realize I had the federal pump.
Anyways now it's leaking like a sive at the valve body where the return line clamps on.
Is there a gasket that goes there. When I swaped it, it did not look to have a gasket or silicone. I put a new o-ring, maybe it is the wrong size! The other passage looked like it had a built in rubber gasket. I cleaned the faces real well.
Any suggestions. I haven't taken it apart yet, I wanted to see what you guys on fabo thought first. :banghead: