Welcome to the forum!
The 700E Hudson locomotive was only manufactured during the pre-war years, and is distinguished by the road  #5344 under the cab window. It was a scale model, and the most detailed of the Hudson locomotives Lionel made until recently.

Other Hudsons were made, namely the 763 and 773, but they were not as detailed as the 700E was. These Hudsons had the 763 and 773 markings under the cab.

Here is a listing of a 700E that was sold, to give you an idea of the price range you are looking at. http://www.dakotapaul.com/items/showitem.asp?iid=2915

Here is a listing of a post-war 773 that was sold, also for the price point notation. http://www.postwarlionel.com/cgi-bin/postwar?ITEM=773

Larry