The 9020s as central processors are all gone from operational sites since the early 1990s. they were canibalized for spares right to the last so doubt there is much left.
9020Es used as i/o processors were around a little longer, but are all gone now too.
There could be a few pieces, or whole machines, left at the disposal section at the FAA Aeronautical Center in Oklahoma City or at the Operational Support Service at FAA Technical Center in Atlantic City.
How come it is the ARTCCs that get all the ink? TRACONs aren't sexy, I guess. The ARTS started as a 256K core memory machine (and I mean core memory) and has been upgraded over the years. Processor was from a Navy design, programmed in a proprietary language. NO information security problems because it got no instructions over any phone lines and only a few people knew what the software looked like. Now days the hardware platform has been swapped out for a VME bus based architecture that fits in a small file cabinet size box. Same basic architecture is used for EARTS (Enroute ARTS). Now ATC systems use UNIX and other commercial off the shelf operating systems and are monitored, controlled and maintained remotely and everyone sweats how some kids in the basement of the science building (or worse) will hack in and cause goodness knows what havoc, so millions are spent on information security. What a racket.