If your pliers should of had plastic jaw inserts the design patent (of June 19, 1956) for this type of pliers is here:
http://www.google.com/patents?id=PxdyAAAAEBAJ&printsec=abstract&source=gbs_overview_r&cad=0#v=onepage&q&f=false
At the bottom of the page there is this note: "References cited in the file of this patent. Plomb Tool Co. Catalog 4820, 1948, page 36, items 236 and 240."
If anybody has access to this catalog it might have the answer as to what purpose these pliers were mad for.
(http://i222.photobucket.com/albums/dd3/buswrench/message-board/jaw-insert-pliers-patent.jpg)
I came across these today. They were on my Phtobucket Message Board Page so I must of posted them here before the crash.
(http://i222.photobucket.com/albums/dd3/buswrench/message-board/Utica-Catalog-661-electrical-pliers-1.jpg~original)
(http://i222.photobucket.com/albums/dd3/buswrench/message-board/Utica-Catalog-661-electrical-pliers.jpg~original)