The 2nd filter people are mentioning could be the strainer that is on the fuel pick up in the tanks.
They tend to degrade and crack after 30 years..

 

I guess I should check my FSM and see what it says. Either way, I agree, and it's been my experience, too, that some things can vary quite a bit between years.

 

If you installed a new oil pressure sending unit and the oil light still comes on and the engine still dies you most likely have an electrical problem. The problem could be in the dash gauge cluster itself. The wiring problem could effect the ignition coil operation (tach operation). Remove the dash gauge cluster and look at the rear of the cluster, where the solid state wiring and connections are with a magnifying glass. See if anything is burnt, cracked, scratched, etc. What could be happening is one of the solid state circuits is damaged and after some use it heats up and causes a momentary short. Unplug your tach wire in the engine compartment and see if the engine dies when the oil light comes on again.

 

Does it die even when you keep the rpms up or when you idle down, such as when you step on the clutch? Are you sure the light comes on before it dies or just after? As soon as the engine dies or reaches a low rpm, low enough that a worn oil pump will no longer produce the required pressure to keep the light off, the light will glow, it might seem as though the light comes on before it dies. Either way low oil pressure won't kill the engine, unless it is seizing. The fuel cut off solenoid will kill it at low rpm if it is not functioning properly though. It can be intermittent if wires are not connecting good, corroded, breaking, or if the ground is not good.