Need help on finding the battery that fits my 2001 V6 passat

Call the local VW dealer's service department and/or check your owner's manual.

Nor does it have to be. As long as the CCA is the same or greater than the old one, you are all set.

CCA is the same or greater

Thank you. Your reply is very helpful. The new battery CCA is definitely much greater than the old one. My only concern is that since the new one with smaller physical dimension than the old one, it may move around when the car is moving.

VW used batteries of several different physical sizes so as long as the CCA is equal or greater you will be OK>

Probably doesn't apply to your car, but here goes. 88 Fox wagon. Famous parts provider/retailer provided replacement. The battery tray had no hold down bracket. Replacement seemed a wee bit taller. Battery tray is under aft end of hood, sitting midway between center and passenger side. After swapping batteries, going down the (rough) road in a residential area, engine stopped running. Smoke under hood. Battery positive terminal had made contact with hood. Didn't last long as the positive cable burned in two. The plastic protector that was on the positive side battery terminal was nowhere to be found.

After repairing the hood, triple coating the underside damaged hood area with 1 coat primer and 3 coats of paint, and replacing the positive end cable, replaced the battery. Same outlet. They confirmed they sold me the wrong battery. Replacement was about a .5" shorter. Made all the difference.

It did when it came from teh factory...

Not a surprise...

You have put in the clamp, right?

Sorry, no inline responses from me. Car didn't come with a hold down for the battery. Haven't found one. Its a one side jobber per the Bentley manual. Exposed metal/rust from the hood reenforcement along with the too tall battery were both contributing factors. Problem occurred almost decade ago.

You're driving around with a loose battery? Good luck!