Where I live, it is common that people put things they don't want anymore in a box at the side of the road and stick a note on it : For free, to take away. Most of the time there is only junk in these boxes but last week I found this Sony WM-51 Walkman with an unbroken plastic case and very few scratches. It features auto-reverse, CrO2 -switch and a mechanical lock-switch, no Dolby. Not really a nice or small device but with the built-in headphones it is a quite funny walkman. Rarely these headphones are even still on. The motor was blocked because of a melted belt and the left headphone was dead due to a defective coil. The coils of the first iPod generation have pretty much the same dimensions, so I used one of them. Only the grey rubber ring doesn't fit anymore. Now I can even better distinguish between the left and right earphone. I'm happy with that find.
I agree, that's a super find! I have yet to get my hands on one of these. And yours seem to be in immaculate condition. Even the stickers are still perfect! Just last week, I too got another one of those walkmans with retractable headphones. This one's quite interesting since it's got an inline remote as well. The earphones and remote are one single piece but they retract separately. So you have 2 spring loaded cable reels. One inside the walkman, and the other inside the remote. Sadly my unit has lost its earphones...