WARNING: Tube/Valve amplifiers use potentially LETHAL HIGH VOLTAGES.
Building, troubleshooting and testing of these amplifiers should only be
performed by someone who is thoroughly familiar with
the safety precautions around high voltages.
If it's a hefty one, what you've got is an autoformer. If you've got a pair of them, you could make someone with an OTL and low-impedance speakers very happy.
About the only use I can see for this inductor is in making a narrow band EQ. I have contacted White instruments but haven't gotten an answer from them yet.