Gentlemen,
It appears that one or two memories have faded. The NY EDP was the original, it was replaced by the Vickers (which caused trouble) and subsequently by the Abex which was good. They were not supposed to be "mixed and matched", but owing to budgetary constraints (ie being tight or skint) they opted to use the new Abex on one system and the older and less reliable on the other. Try
http://www.lockheedmartin.co.uk/cont...News/V10N2.pdf for a further explanation.