How do I tell if I need a 100 amp or 130 amp alternator for a 2001 Lexus rx300. I already have an aftermarket alternator so I don't know what the original is.

SOURCE: I need to replace the alternator for my wife's 2003 Lexus RX300. Do I buy a 100 amp or a 130 amp alternator, and does it matter?

you need take old alternator with you to auto parts stores they can match up your alternator give you the correct AMP TYPE, your alternator amps is stamped on the out side alternator housing, the auto parts store can look up right amp alternator for your vechicle.when you say dont matter yes it does if you get wrong type alternator, your battery wont have good charge causing alternator fail early and battery fail early.

Testimonial: "Thanks. I assumed this was the case, but you have helped me locate the amp signature. I appreciate this help."