Approx. 1 volt drop between battery and fuse box

This question concerns my 1978 D-300, but I hope nobody objects because it has basically the same electrical system as other Mopars.

With the ignition in the "run" position but with the engine off, I get about a 1 volt drop between the battery and the fuse box. I guess I should try removing the fuses to see if removing one of them makes the voltage drop go away, but before I do, can anybody tell me if this sounds anywhere near normal?

I can make exact measurements at the battery and fuse box if necessary.

Does the ECU really load the system enough to cause that much voltage drop, or must something else be drawing current when it shouldn't? Or maybe a bad connection at the bulkhead connector?

Thank you very much for your thoughts.