I know this is an older thread, but it is extremely helpful. I recently had an EGR code and after some testing, determined it was the EGR valve. Bought this one from Amazon:
Amazon.com: ACDelco 214-5073 GM Original... and it works perfectly. I did a lot of research and part number lookups. This is the Negative EGR. Part number 214-5073. It is made in China though...