Here’s a rare one from the 70s by Ibanez. It was originally marketed as the OD-850 Overdrive II (not to be confused with the OD-855). But since the nature of this pedal is more distortion/fuzz territory, it wasn’t a great name and it was changed to the Dirt Box. Whatever you want to call it, the circuit is essentially a Distortion +/DOD 250/Ross Distortion with a dual op-amp and a Tube Screamer-like tone control. The 220n capacitor coming off lug 2 of the Tone pot was originally a tantalum cap, but like the Tube Screamer, using a film cap should give better response. The sound is apparently similar to the op-amp version of the old EHX Muff Fuzz (the one that plugged directly into your guitar, not the BMP).
