pulleys on a 302
PS pump and water pump share a belt. Should go on the rearmost groove of the crank pulley.
Alternator uses one belt and goes to the center groove on the crank. I think some trucks had dual belts on the alternator, but that may have just been a PO's mod after removing the smog pump and its little belt (it ran off the alternator's double groove pulley).
AC compressor uses one belt and goes to the outermost groove on the crank.
Now if it's a serpentine setup, I can't say since I've never worked on one. What truck do you have, anyway?
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