There can be several different issues.
One:
Trucks with ammeter and oil gauges are wired drastically different than trucks with idiot lights between the regulator and the ammeter and ignition switch.
Those connectors from autozone and napa are for alternator warning lamp equipped trucks. I'm going to assume your truck also had warning lamps from the factory because the plug matches these.
The connector from your painless harness is either for ammeter and oil pressure gauges equipped trucks, or it doesn't have the wires for the electrically assisted choke or the alternator radio supression.
Truck has the factory gauge cluster with the following:
Brake light
Oil gauge
Fuel gauge
Speedometer
Temp gauge
Ammeter gauge
Low Fuel Economy light
Two: 1975 trucks use Duraspark-I ignition modules with green grommet. These are wired differently than the 1974.5's with Duraspark-I with black grommet, and the 1976 and later Duraspark-II.
The instrument clusters for 1975 can have a unique printed circut than the other years.
1975 was a one year wonder for wiring, so it's important to match it closely.
Old module was Motorcraft w/7 wires (including blue wire) and green grommet. I replaced it with a new module that has the same wires and green grommet.
What year is your painless harness for? It has to be for a 1975 or there will be problems.
The Painless harness is kit #: 10118 - For Ford F series trucks 1967-1977. There sections of the manual for different year trucks.
http://painlessperformance.com/webca...manualIcon.jpg
I'm going to need pictures of the connectors around the voltage regulator, ignition module, starter solenoid and alternator, to see what might be going on.
I will take a bunch of photos showing all of the areas you requested. Thank you.
Also need to know if the truck has ammeter and oil gauges or warining lamps from the factory.
Ammeter gauge and oil gauge from the factory - not lights.
To fix this it's going to take pictures and questions as too many changes have been made to the original wiring to try and help you by just looking at the 1975 wiring diagrams. Need to see what shape the wiring is in now.
Thank you for the detailed info. I will get those pictures shortly.
