a Magnum Pro Select D-10 Double 10-string pedal steel guitar
A "secret weapon" on Siamese Dream, notably on the Cherub Rock solo, this pre-amp was pulled from a pedal steel guitar, which was built for a much lower output than a normal electric, thus producing a "super high-end white noise gain that gave the guitar this sonic jet sound." (-Butch Vig, EQ Mag)
Pedal steel guitars are basically body-less guitar necks laid flat on a platform, with several foot and knee pedals to adjust the tension of the strings. Many use 2 necks with 10 strings each, in C6 and E9 tuning.