For what it's worth I did a voltage drop test today. I turned on both fans and measured the drop on both the positive side and the ground side. The positive side was higher than I would have liked at 1.32 volts. My fan relay feed is wired directly to my alternator stud. There is only a #8 to the battery for the alternator so this may require a rework. However this was with the car not running. Anyway the ground side which consists of 6" #1 cable from battery to cage, 6" #1 from the torsion bar crossmember, transmission bolted to the engine, engine bolted to the motor plate, ground for the fan at the plate. The ground side voltage drop was .03 volts. Though not completely scientific it show the ground side to be more than adequate for a fairly strong amp draw. I didn't have an amp meter handy to measure but I would guess 25 amps + for the pair.
Doug