all of the efi related engine wiring is in one harness, that goes into the truck via the bulkhead on the passenger side. There is one take off that goes down the the back up switch and the o2 sensors as well. On the inside three plugs go to the ECU. In the same local are two multi pin plugs that send wires up into the dash and back to the fuel pump. There should also be another plug under the passenger seat on its way back to the tank. I would guesstimate maybe 20 wires combined in the two plugs that go up into the dash. I want to say those two connectors are C1 and C2.
