I do believe CARB stands for California Air Resource Board, meaning if it’s on the label it’s CARB approved, yours is a fuelie tank that connector is for the fuel pump.

 

It just has a sending unit under the panel with a petcock for carb. I was reading the tank is off a 04 carb(erator) model.

 

 

Interesting...

I too, believed that the EFI softail bikes had the large removable panel in the center of the tank, for the EFI pump and fuel gauge float assembly....





I also believed that all the Carb model bikes, had only the hole under the faux gas cap, where the fuel gauge float assembly mounts....






But then I also found this float assembly, that has no fuel pump, and that mounts through the center panel of what I thought were only EFI tanks....?!?!?



So it looks like it's for a Carb bike...?!?! I have an "01 Springer Carb, and an "03 Heritage EFI that both follow what I previously thought was the rule...

My best guess, after a quick parts search (it was a quick search so don't take this for gospel)... it looks like in 2004... the softails all used the tank with the removable, large center plate that mounted either the carb fuel sending unit, or the EFI pump/fuel sending unit... It even showed two different top plates for that large center hole, depending on fuel delivery choice...

I know this is an old thread and the OP is long gone, but I just did a quick search to find this info, because the posted pic made me curious...

 

I think I got my issue figured out. After tons of calls, I came up with this. I am building my own Harness from the tank to the gauge. Its the direction I will be taking.

My application I put together.

The newer tank with fresh paint

 

I converted an dual line EFI tank for carb use. Pingel makes the plug and adapter.

The EFI is a better tank due to the top plate. You can remove it for access. Helpful when you want to remove the liner after it falls apart.

The gas gauge is okay to have but I always odo the miles.