I saw a factory stereo setup in a 2nd gen this weekend. Full sized radio(only) sitting in the top dash slot/radio position and a full sized cassette player that filled the lower slot where there is usually a storage tray/box.
I obviously don't know if they work, but they seemed complete and in relatively good condition considering their age and that they were in a junkyard.
I do know that the clock from that truck is working great in my truck now.