Almost all of the homes have oil or electric, this is correct... However, you could always call PECO and find out if they can run gas lines to a specific property and if so how much they would charge to do so. Sometimes they are able to if gas lines are nearby and you get a few neighbors who all wish to convert, worth a shot!
If you would like to view any homes in Levittown, please let me know as I would love to work with you. You can also set up a daily listing alert on my website, http://www.kimberlyrock.com