I went out and bought a new ERG valve the one I got from the auto parts store looks identical to the old one. Well the old one didn't have to oem part number on it and had a #10 orfice washer in there. So for the time being I have a #10 in the new one. Well anyway I called the chevy dealer and found out the oem part number but it's not on the sheet that came with the EGR valve. Any ideas on what it might be or what the orifice size should be?? I have a 88 iroc 305 TBI.