I'm too old to figure out why my pictures come out sideways. Anyhow, about to send 3. I ask about all 3 "what's this". Not that I can fix anything. Just want to know what it is/does in case it bleeds. This sits to the left of the fuel filter. Has what looks like plumbers putty on it. Was zip tied in place? Guessing that is not a standard Detroit mod, so I just tightened the nut that holds it in place and will cut off the zip tie.