As anyone who reads what I post in the forums, I'm obviously a big fan of Dano and Beavisaudio.com. I recently asked the group about a Walrus Audio circuit, to which everyone seemed to think it was a derivative of the ProCo Rat. I thought to myself "Where else have I seen a Rat with four knobs and a switchable clipping stage? Oh yea, Beavis Audio, of course!"
Lo and behold, the FKR. There's an extra knob added on the amp supply, known as the Ruetz mod, or colloquially, the "lube". Also, in true Dano style, he tossed on a daughterboard with 5 switches and a wiiiiide variety of clipping diodes.
uhm..looks like the Beavisaudio site is down. I will have to supply a link to the page on the project later.