Power Steering Pump Question

[thumpernickle]

I am in the process of replacing the power steering pump and reservoir on my 1979 Silverado. I ordered a remanufactured one from AC Delco through RockAuto using their by application selection process. When I got it, the pump was "clocked" wrong in the reservoir and would not fit as the fill tube faced the wrong direction (it conflicted with my A/C compressor). In other words, the mounting holes to mount the pump/reservoir to the engine mounting bracket did not line up. They were at about 1 and 7 o'clock in relation to the fill tube. On my original pump the mounting holes are at about 3 and 9 o'clock in relation to the fill tube which allowed the fill tube to face away from the A/C compressor.
I have since gone to NAPA and O'Reilly's and their by-application computer result gives them the same thing.
I have also checked my father's 77 and 75 trucks and they are the same as mine.
What do I need to do to get the correct power steering pump? Do I need to specify A/C? What application uses the power steering pump I received from RockAuto? Any information would be greatly appreciated.