I can tell you now, oil pumps rarely fail.
I can almost guarantee the oil pump is not the issue. You more than likely have a sticking oil sender, it's going bad, or the wires rubbing or that "frequency" at that specific RPM vibrates.
I'll see if I can post a diagram of the sending unit location.
I couldnt find a "wide angle" shit of the location, but I can tell you how to find it with the aid of a closeup view on the diagram. Sitting in the vehicle, the oil sender is on the right rear (by the firewall) side of the engine. Almost by the bellhop sing of the trans but it's on the engine block at the end of the cylinder head.
https://www.dropbox.com/s/424pxckw7p...54.09.png?dl=0