Here we have a vintage MXR distortion plus pot code dated at 1978. It has the desirable ua741 806 op-amp chip. I’ve had this Pedal since the early 80s.
It is in pretty good shape considering It’s age. Please look at the photos carefully. It has the script logo on the back plate and block logo on the front. If you do some research, you will find that this Is what they did in the late 70s.
I have cleaned out the deteriorated foam that these had inside of them years ago. 
I replaced the foam they covered the circuit board with a thin piece of cardboard folded over the circuit board to protect it. This is a much better option than foam.
It is fully functional and sounds as it should.
Look at my pictures carefully and ask any questions before you bid or by. If you look at the chip pictures and the pot photos you can Google the numbers and get a lot of detailed information. This is a pretty infamous pedal that sounds killer with a great tube amp like a JCM 800 or plexi.
I pack things well and ship out fast. Check my feedback and bid with confidence. Thanks for looking.