I think John's memory was tricking him, Who's Next sounds totally like a Thunderbird to me. He might have used Frankenstein for some of it, but I can't think where. Maybe on WGFA as the recording quality isn't as good as the rest of the album, he could be playing anything... although on the other New York sessions of the time it still sounds like a Thunderbird to me.
Listen to this - a Thunderbird without a doubt (ignore the pic! 😆)