1) Try looking for the movie "Die Hard 2 or 3" I am not sure which
(about terrorists seizing a building) Although this film is not about
the M8 or M20 it has one in it.
2) I have an M8 Greyhound Armoured Car (driveable)so will be interested
if you can find anything. I have not had any success except for the odd
TV news item about South American events, where occasionally you will
see an M8 used for crowd control!
3) I could be quite wrong here (no doubt that is leading with my chin)
but virtually all WW2 American vehicles with "M" designations and most
aeroplanes were named by the British, as they did not commonly use an
alpha numeric system. Thus the correct spellings would be in English not
American English ie: M8 Greyhound (not Grayhound), M3 Stuart (not
Stewart) etc.