You can find them anywhere really.
www.camaroz28.com
www.ls1tech.com
www.ls1.com
www.ls2.com
www.traderonline.com
Are you wanting a Z28, or a 6 banger? If a Z28 get one that came with the Z rated tires. If not it will have the 6 cyl gauges and have a speed cut off at 108 mph.