You might find help at a motor factors, especially one that deals with truck parts.
I believe that AC-Delco ceased around the time that Bedford Trucks folded. GM spun-off the electrical component business and it became Delphi (though GM retained the ACDelco name and have since begun making replacement parts for vehicles - such as brake discs - using this name).
Most motor factors have catalogues that list parts for various models (though I'd be surprised if they went back to 1950), but, if you can find a long-established business you might find a link for what you need.
This might help:-
http://www.ebay.co.uk/itm/AC-DELCO-M...item4d05aab0da