My 70 conv (excuse me, my wife's) has 3 crank pulleys, 3 belts. It was a 307, now SB400. The ps is low left side with 2 pullys and ac above left. Alt is right upper. The rear belt is crank/ps only. The middle belt is crank/ac, but just rides a little on front ps pulley. The front belt is crank/water pump/alt. The ac belt does not touch the water pump.
My son's 71 BB, which used to be a SB, was the same.
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