That started with one person on a Imperial forum web page many years ago. Vendors of solid state regulators simply ran with that info rather than investigate this application/assembly.
I'm going to leave the IVR and gages alone assuming they pass the remaining tests. Since the fuel gage worked OK, and the oil and temperature senders were getting less than 5 Volts (need to find my notes on exact number) I suspect the problem is in circuit resistance. I need to prove or disprove that.