Actually, they were removed from the army gazelles because every time you operated the radio, they fired off (well-designed looms, those)! We had them installed on the LongRanger at Alton Towers, and a good thing, too. Perhaps I detect a sneering tone on this thread about them - they're not a quaint British idea, as they were invented in the US, and anything that saves my a$$ gets two thumbs up as far as I am concerned!
phil