Being a fuel injected Diesel means that there has to be a return or overspill line from the injection system back to the fuel tank. This truck has the factory duel tanks and the pictures here are from the lower one. I pulled it out and after draining it, washed and removed the rust ready to receive a coat of Zero Rust (even though it’s cad plated the plating has been breached in a number of places and it was starting to rust). Here I turned the threads off a brass 1/4” NPT to 3/8” hose barb fitting from home depot and drilled a 7/16” hole near the filler neck and vent. I figured this was as good a place as any for the fuel return. I’m not going to show you pictures of the fitting after I brazed it in place because my brazing sucks and I had far too big a torch tip so I made a bit of a mess trying not to blow through the steel of the tank or completely melt the brad of the fitting. Suffice it to say it’s brazed well enough to hold a liquid tight seal. I never said I was a welder.