I think he uses an electroharmonix POG to get the octave effect, but those are a bit pricey, you could try for something cheaper.
He isn't using the Muff in that video until the end.

That is the Silvertone amp, I think. I'm about 70% sure he wasn't using the POG back then, and it's just a Digitech Whammy.

He uses the Muff at the end, at 2:05. Before going in to Jack The Ripper. You gotta remember his Muff is a seventies Muff, different to the modern ones. Usually, it's all the controls are just over half way.