My 70 Cutlass steering box has a small leak. Fluid is coming out through a hole at top, at the front of the case. From the service manual, I think all I have to do is rotate the retaining ring and the case cover will pop off and replace the O-ring. I am having an issue finding this O-ring. The case appears to be the original Saginaw gear box. Any leads on who supplies just the O-ring seal

 

Try calling this place.

http://www.powersteering.com/

 

You may want to consider taking this opportunity to replace your steering box with one with a better turning ratio. A 92-98 Jeep Grand Cherokee steering box swap is inexpensive and a very good upgrade. The company linked in the post above can also rebuild your box to a 12:1 ratio. There is a thread on the GC swap if your interested in learning more about it. Just do a search for it.