Way back in 1969, I heard "Inna Gadda Da Vida" for the first time. I realized quickly after building some simple transistor stages that didn't work properly that "the" sound was coming from abused transistors! Experimentation over some weeks led to [this circuit]! Just two pots give an amazing range of distorted sounds and none of the components are critical.
Please tweak away until you find the sound you want! Alter capacitors, change the transistors–experiment!
The original FSB thread with the schematic can be found here.