All you need is an old chrome Morley Power Wah Boost(hard to find, but try ebay), and a real good distortion(something like a big muff pi or whatever else you got). You can get some of the most awesome sounds from it. The PWB is a quite noisy though and you'll have to have a good amp and turn the volume up loud. It also brings out the dist/wah better if you put the dist. first in line. You can get Cliff Burton sounds, like off anesthesia pulling teeth. He used just a Morley PWB and an overdriven amp.