This is an ad from the "Edison Electric Institute"
touting the benefits of electric heat. As you can see
below, East Central was one of their shining examples.

This ad appeared in a national publication in the 70's.
Here's an interesting bit of trivia.........

The architect of East Central, William Henry Ryan,
also designed the Rose Bowl bowling alley, and that
funky looking church up on the hill in Broken Arrow.