1. One is located at the University of Stuttgart in Germany in a museum run by the computer science faculty.
2. Bob Rosenbloom's collection way out in California contains several analog computers and he has two Donner 3500 computer.
3. Bill Degnan a collector who specializes in Commodore computers but has a talent with all sorts of computers is restoring a Donner right here in Pennsylvania.
4. I was recently (Dec 2013) contacted by the owner of a 3500 who is looking to sell it. We did not find out where it ended up.
5 & 6. There are two in our collection. One is an early Donner computer. The other is a later Systron-Donner that was located near Atlanta, Georgia, USA and was owned by a gentleman who designs robots near Atlanta, Georgia.
--We have an unconfirmed report of another Model 3500 at SMECC (Southwest Museum of Engineering, Communications and Computation) in Glendale, Arizona.