KDS-15
The portable version, cataloged as the KDS-55, was a very nice machine.
Have you had a portable before? If not, here's a tip that may save you some grief - be sure your kitchen floor is in really good shape. Portables are heavy (vintage being heavier than new, of course), and they're even heavier when fully loaded.
That means they can wreak some havoc on a floor that's not sturdy and in good repair. If someone has cheap no-wax vinyl, or old VCT tiles, or a funky subfloor, a portable is going to do some damage. KitchenAid vintage portables have larger casters of better quality than many machines, and tend toward less damage, but the problem is still there.
And make sure none of your new acquisition's casters are stuck in one position or have a flat spot - these conditions will just make things worse.