On the CAN-BUS Fords, the fuel gauge strategy is a little weird. The sender mostly tells it when it's full, then the PCM counts injector pulses to meter the fuel gauge. That's how it keeps it from fluctuating with hills like our older vans. And it also why adding 5 gallons won't always register on the gauge. And also why it even has a fuel sender code. But it might be ignoring the sender at this point, if it "knows" its bad. This might be one of those items where you need to actually pull the battery lead for 10-15 minutes to clear the KAM (keep alive memory) and make it recognize the new one. Does the SCT let you do a gauge sweep test? That would be easiest way to rule out the cluster.
The pickups have a gauge-sweep mode built-it, where you hold the trip-reset button while starting up, until the test lights go out, then it sweeps when you release the button. Not sure if this work on the E-series.
2000 E450 dually V10 wagon