If i purchased a alternator from Deer River O Reilly's. Can i return it to the Brainard O Reilly's? Or dp o have to return it ti the same store i purchased it?

Yup. Any O'Reilly's

they are nation wide returns and warranty. .

Any O'Reilly's Auto Nationwide will return, or warranty items as lon as there is a corresponding part number in their system.

You can return it to any O'Reilly if you have the receipt or the card you paid for it with

Yes you can