[68c10airstream]

Spent about 1/2 hour on alldata pro and found conflicting info. So to help out i looked into fuel pump system and oil pressure sender and finally found the 3 wire electrical diagram which contains your oil pressure sender and your backup fuel pressure switch all combined into one plug in at one unit. Tried to find an illustration but no luck.

I remember an argument with our parts manager about trying to get the right part to fix a gmc of about your vintage. After a lot of looking i took the part off and ran the part number through out parts system and i believe the part was under the fuel system, not oil system.

Anyway from my old man memory look at the base of your distributor and look for a long silver cylindrical unit, about 4" tall, 1" diameter, installed horizontally or vertically with a 3 wire plugin containing a tan wire amongst the wires. I remember having to buy a specific snapon socket to fit in there to remove it.