It's suppose to be on top of the engine under neath the turbo cover. Does anyone have a pic on where its located and what it looks like?. Not all 6.5T have them. Has to do with the exhaust being pumped back into the engine. My tech informed me to see if I have one. If I do to remove the vacuum hose and clog it then put it back on. Said it will increase MPG and it wouldn't hurt the engine.