Which alternator is correct for my car, 150 or 170?

Hello,

To find out which alternator is in your vehicle, you will actually have to call your local Chevrolet dealer and talk to the part department. Provide them with the VIN and they will be able to tell you which alternator was equipped from the factory, 150 or 170 amp.

I have attached the replacement procedure below for your reference.

Let me know of any questions.
Thank you.

https://www.2carpros.com/articles/how-to-replace-an-alternator

The old alternator should have a part number on it. If you can give that to us, we can tell which alternator you have. In general if there are no large accessories you will have the lower amp alternator.