I have a 1999 Chevy Suburban that needs a new alternator. How do I determine which one I should buy?

Write down make, model, year, engine size should be found under hood and in door jam and take info to parts store, should need basic tools such as half inch, nine sixteenth, possibly five eighths and three eighths quarter inch wrenches and sockets and a pry bar to pry up alternator and get belt nice and tight

Autozone sells rebuilt alternators with a lifetime warranty.