1971 Slant-six ballast resistor ID

Not sure but others with 71 knowledge should chime in today.
Nice clean looking engine compartment.
I'll just throw this out there...
It appears the 4 wires is for the 72 and up, 4 prong resistor. (that 4th wire is throwing me off).
Is that original wiring on your car?
I dont remember a ballast resistor mounted like that on a fenderwell, usually on the firewall.
Also, usually a 7/16" galvanized stubby self tapping bolt head holds them in place. (hard to see in pic, but this location is def correct).
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