Here's a weird one for you–the Shin Ei Octave Box. It's apparently an all analog clean octave down effect. I'm not going to pretend to understand how it works, but there are a lot of transistors. Originals used 2SC644 and 2SC666 transistors, which I think were in the massive TO-3 package. I've drawn the layout for more modern replacements, BC547s and a BC557. Other transistors like the 2N3904/06 or 2N5088/87 would probably work as well. Socket and experiment with what you have on hand.