[papajam]

If I'm reading the parts books right, the single speed 3-wire wiper motor for your Duetto, Bosch #0 390 326 002, is the same motor that's in our 68 GTV which has two speeds. I have a NOS motor in the parts pile so if you can wait a few days, I'll fire it up and get some wire color codes for you. I'd think though that there might be a little rewiring to do at the 2-speed switch and perhaps the footswitch as well.