Building the Disarray currently. I ordered 51v zener diodes but they're too big to fit. I couldn't find anything for "51E" from the build doc "51E 51V Zener". Is there a specific diode that anyone has used for this build?
Strange circuit that one. ANY zener >3V that will fit in the holes will work. Not sure why the original designer chose zeners because they never get a chance to do their zener thing, they only conduct in the forward direction. That blue LED clamps the reverse voltage on the zeners to <4V. For that matter, you could use 1N4148s, it's not going to sound any different.
The effect of the different diode voltages could be pretty subtle and dependent on playing style, pickups, amp, etc. A YouTube video is just that. How it sounds to your ears is really all that matters.