Oil Pressure problem

I have a 1984 F150 that after driving down the highway at 65mph loses oil pressure suddenly. It goes all the way to the left. The engine temp is normal as long as the engine stays running. It has a 351W with 163,000 miles on it. Any help is greatly appreciated!

I wuld suspect that the oil pressure sender is bad, and not that you truely have critically low oil pressure.