My 454 has two belts going from the alternator to the pulley, also both the alternator and Power steering are on the driver's side. Will both these accessories being on the same side with nothing on the other throw it out of balance? Also, what is the purpose of two alternator belts?

I don't think you have to worry too much about balance of small external parts like alternator and power steering. Your crankshaft main bearing may be slightly happier if the belt tension was directed to both sides of the engine instead of all to one, but probably not enough to worry with. The dual pulleys are just to double the amount of power that can be transmitted to the accessory (and seemingly quadruple the amount of headaches in making sure everything is alligned and tightened properly)

A friend of mine used to run double pulley on his set-up. The thing was chronically squealing and throwing belts despite our extensive efforts to insure that everything was well aligned and properly tensioned. I hope you have better luck!

When you buy belts you have to get a matched set. I don't know if automotive belts are available that way. Belts used in industry are.

Originally posted by Pat Kelley:
When you buy belts you have to get a matched set. I don't know if automotive belts are available that way. Belts used in industry are. Yes, they are available, the sales rep from the respective belt supplier will tell you that all the belts of a particular size are matched, they,in fact, are not, you have to match the batch numbers on the edge of the belts.