The Unimat 3 was discontinued when the Unimat PC was introduced. The PC was a nice machine with some weird idiosyncrasies. The PC was designed as a hobbyist lathe that could be easily adapted to CNC using Emco's proprietary software. It was rather pricey. Overall the PC was a more robust machine than the 3/4. The power feed was very well engineered. The biggest failing was a bespoke VDO motor that was nearly impossible to swap for another motor. The Sherline blew it away in the marketplace.
The Unimat 4 was pretty much the same lathe as the 3 but introduced after the PC pretty much failed in the marketplace. If I remember correctly, the 3 was made in Europe and the 4 in Taiwan. It is disappointing the PC failed. It was a very nice piece of equipment that with a few engineering flaws.