Upgrading Alternator

So today for the first time I think I found why my wipers are not working. With the key in ACC position the wipers work fine but driving they don't work. Well today I noticed the Ammeter would drop to near 0 when they would sweep across the windshield. I also noticed at night my ammeter would show low with the lights on. So I am thinking my Alternator is not providing enough amps. Does anyone have an model/item number for an Alternator that fits but provides more Amps?