Billy is quoted in an April '96 issue of "Guitar School" magazine as having used a Digitech Whammy on "Bodies" off of MCIS at 1:56 to drop the harmonies a whole step. Given the timeframe of the recording of MCIS (Mar-Aug 1995), the only available Whammy models at the time were the WH-1 (which was discontinued in 1993), WH-2, and original Bass Whammy. If Billy only used the Whammy on this track, it is possible he borrowed James's whammy, which was a WH-2 model.
The Digitech Whammy emulates a whammy bar with a foot pedal, allowing the guitarist to shift the pitch by up to 2 octaves up/3 octaves down, without worrying about breaking strings or going out of tune. It also has various harmony modes, and a detuner.
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