This ad does not specify diesel which mine did Let me try to correct

 

EDIT: My truck already has this in both tanks. I can see my tubes from the inlets.


Maybe your filler assembly is there but someone removed the inner breather hose.
I thought it was all stock since the parts looked original.

 

The ad posted now is out of stock but thanks for the info! A similar mod has been talked about on here for a while now. Now the body shop says their insurance won't let them allow a customer to work on his vehicle in the shop. I'll see if I can drive it to a vacant lot next door when the bed is off.