1984 6.9 idi rebuilt and now has about 3k miles since the build. The engine runs smooth, no unusual noises, and delivers 21 mpg highway. Recently the oil pressure has dropped to the bottom line of the normal range on the factory gage. I figured it was just the factory gage being nothing more than an indicator that oil pressure is present. I put on a new sending unit and this did not change the reading. I checked voltage at the wire that connects to the sending unit and voltage is present (this is an indicator that the ICVR is operating). This old truck has a low voltage instrument cluster with a voltage regulator that feeds the temp, fuel, and oil pressure gages. I installed a direct reading gage and confirmed that at idle the pressure is not enough to register, and high rpm the engine develops about 17 psi. My diagnosis is probably a stuck oil pressure regulator. When I pulled the oil cooler I found that the pressure regulator is staked in and not easily removable. A search around here disclosed that a replacement part is not available for this engine. Ford has discontinued this part and no alternate part is available. And there is no overhaul kit to renew the existing regulator. My idea is that I need to get the existing regulator out of the oil cooler header without bugging it up. Then I MAY be able to polish the plunger and bore, if necessary, find a replacement spring. My question is: has anyone else had this problem, and what was your solution? Thanks for any advice that you all may provide. Is this Ford's way of telling me to buy another truck?