What in the wild world of sports is this?

[Jim993]

When I got my '85 6.9 in 1998, the factory water separator was there but disconnected. I took it out and have run with just the main fuel filter up on top adjacent to the injector pump for 120,000 miles, 22 years. I do change the main fuel filter every 15,000 miles and inspect the old one for water in the bottom, never have had any. Truck is garaged.

 

[Scotty4]

Thanks @Jim993 I figured that’s what it was as it looks just as old and dirty as everything else down there.