5 blade vs 7 blade clutch fan

I tried several different factory fans between 99 and 2000,including flex-fans, smaller 6-blades and the large Mopar 5-blade/ viscous drive.
Nothing did the job until I installed the 7-blade.
That 7-blader has made thousands if trips to 7000/7200,slightly underdriven, since ~2000, the T-clutch went on in about 2002, after the viscous couldn't keep up; same year the Hi-flow pump and stat went in.
That 7-blade was already 27years old when I installed it, being a 1973 model.
The only time I hear it is when it cuts in at idle, and I am standing outside the car. My rad is also a 1973 A/C model, off a 318-Dart.
Not a stroker, just a 367HO.