The black hose is just attached to the return line and lets the returning fuel into the tank at a different location than the fuel pickup to help any air keep from getting recirculated. The black rubber foot now has a piece of stainless tubing ran all the way through it to the bottom to bypass the check valve on the side of it. With this mod I can add about 7 gallons more fuel at fill up without it splashing back on me and the truck runs much quieter not to mention it will save me the next time I get a bad load of fuel and it prolongs the life of the $20+ fuel filters by prefiltering with a $5 fuel filter.
Here is a copy and paste from a post I did on another board about this:
I just got done modifying my fuel system and I think it is something everyone should do. About $35 and around 4 hours and I now have a much better truck. It definitely runs quieter and I no longer loose fuel pressure when I get on it hard. In my case I have lots more power on my higher chip settings. But best of all I can get fuel anywhere I want without fear of nasty crap ruining my $300 fuel pump or my $30 filter or my $2000 injectors. A spare filter is $5 and it is easy to change so I keep one in the truck for emergencies. I finally got the pictures of the whole process added to my new picture site and tied to my signature link below.
Here is a materials list and brief description of what I did.
Goldenrod fuel filter assembly from tractor supply ~$25 (Thanks banjo willy)
Tractor Supply Company - FUEL TANK FILTER
About 4ft of 3/8” and about 2ft of 5/16” rubber fuel line ~$10
Make a bracket/mount for the fuel filter
3/8” compression union
About 6” of 3/8” stainless tubing
3/8” hose barb to 1” pipe fittings
5/16” hose barb to 1” pipe fittings
About 6 or 8 small hose clamps
Basic hand tools
I removed my tank and loosened the large plastic nut with a block of wood and a hammer. Make sure to measure the total length of the pickup assembly before removing the white plastic mixing valve thingy. I then removed the screen in the foot and pushed the 6” tubing all the way through the foot past the check valve. Put the compression fitting on the factory tube and cut the 6” tubing so that when you assemble everything it is the same length as you measured to start with. I also used a short hose on the end of the return tube to route it away from the pickup foot but make sure it will not interfere with the gauge float. Use a PVC cutter to snip off the two plastic pipes that hang down into the tank so you can get about 6-7 extra gallons of fuel into it without it spitting out at you when filling. Reinstall the pickup assembly in the tank and tighten the nut, there should be a arrow and a mark on the tank for alignment. Put the 3/8” fuel line onto the factory line and secure it with two small hose clamps. Reinstall the tank and use the factory fuel return line and your new fuel supply line. Find a good place to mount the filter assembly and hook the 3/8” line to it securely. Now use the 5/16” hose to run from the filter to the factory electric pump and secure it all with plenty of hose clamps. This will give you clean, free flowing, and air free fuel.