Yep, the two float assemblies are wired is series.
VERY IMPORTANT - The main float assy. unit (the one mounted with the fuel pump) MUST be the one for AWD for the fuel gauge to read correctly when wired with the sub unit. The FWD unit has a different resistance value.
Example: I'm going to use made up numbers here. Both AWD and FWD use the same fuel gauge. The fuel gauge is supplied voltage and the other side of it is looking for a ground through the variable resistor of the float assy. The gauge will show Full at 0 ohms and Empty at 100 ohms.
FWD one float assy. measures 0-100 ohms.
AWD with two float assy. each will measure 0-50 ohms and hooked in series will measure 0-100.
When you hook two resistors in series, the ohm value of each is added together for the total value of that circuit.
In case you don't know what series is, when you put batteries in a flashlight, you are hooking them up is series.