You could see how uneasy shae became when discussing the circuitry in his mod... dave was trying to get it out of him but he tried to skirt around specifics..lol basically the blood switch is an afd switch lol
The overdrive is not mostly diode.. check the schematic again… the overdrive comes from the 12ax7s and then the diode offers a final shaping to the already overdriven tube. It’s been explained in detail on the old metro forum, years ago.