Youre looking for an O2 simulator from Casper Electronics. I would call them up and find the correct one for your application because it changes a lot between chevys of different years. Use this page and just search for O2.
www.casperselectronics.com/Merchant2/merchant.mvc?Screen=SRCH>https" target="_blank" rel="nofollow">https://
www.casperselectronics.com/Merchant2/merchant.mvc?Screen=SRCH>https://
www.casperselectronics.com/Merchant2/merchant.mvc?Screen=SRCH
You can buy it from Summit but youll have better luck talking to them directly.