By the Anacostia Station, walking towards South Capitol Street there is an '87-'88 Flx Metro sitting in a commercial vehicle training facilty. I pass it everytime I go to work, so as of last check it is still there. I think it still has it's bike rack. I am guessing it might be either an 8800 series or wheelchair lift 8900 series, just for the fact that if you are learning to drive a transit bus, you might want to learn how to use the wheelchair lift.
There was another commercial driving school that had an ex-DART Flx B, don't know if it's still there, I saw it last over a year ago. This driving school was on Ardwick Ardmore Road, just leaving MLK Highway.
It actually is a '90 Metro B.