IIRC the mutron is a bandpass filter?
If you are talking about the Mu-Tron III, you can select low, high, or bandpass filtering.Yeah I meant bandpass instead of lowpass like @simeon used
try this as a starter and tweak to your liking. i've no idea what guitar of amp was used in this song, but the important thing is how you set up the filter. low pass with envelope tied to frequency and Q, so you get the "quack". i've run it through a tape drive here, to try and get more of an analog vibe...