Here's a very cool Rat variant now out of production. Fairly straight forward Rat with a variation of the Ruetz Mod, LEDs for clipping and a switch to toggle a feedback loop. On the original this is a toggle (SPST), but would be fun to put on a momentary footswitch. Couldn't confirm the IC in the original, as the markings were painted over. Might be easy to assume the IC is an LM308 or OP07 since it's based on the Rat, but it's missing the compensator cap (30pF cap across pins 1-8 in a normal Rat) so I'm guessing a TL071/LM741, but an OP07 would work too. Fits nicely in a 1590B or 125B. Schematic here