I need help identifying this.

Clamp

 

Egr tuneup

 

Looks like crankcase vent out of rocker cover

 

That looks like the crankcase vent from the valve cover. IMO I wouldn't even call that a seep. Its not even damp. Very unlikely that is the source of your concern. I'd be looking at the exhaust and aftertreatment system.

 

change out the crank case filter and tighten the clamp or perhaps a new one. put her in the big hole and make some money

 

Regarding the pic in the OP, it looks like a blow by hose going into a crankcase filter. The vapor residue there is very common. I see it on mine too, sometimes looking even worse. I clean it every now and then and replace the crankcase filter every 50 000 miles but it does not help a lot if a truck has its mileage. Sometimes, a check engine light would pop out about it too: "Crankcase pressure high" or something like that...