EGR VALVE LOCATION on 1991 Chevrolet Astro

Where is the EGR valve located on 91' astro van

Asked by for the 1991 Chevrolet Astro
My labor guide says it takes .8h to replace so it must be straight forward. I don't have a picture as to its location. maybe look at www.rockauto.com, they usually have good illustrations of the parts and when you see a picture of the part it may help locate it.
Thanks I'll check it