This joke is from Dragon Magazine #50.  Published in June, 1981.

Sadly the cartoonist isn’t credited, but I think that it reflects how long there’s been a desire for creators to armor female characters as heroes and not as pinups.

– wincenworks

edit: The cartoonist is John A. Morgan. We updated the image to one without the artist’s credit cropped out. (ht: cmccrzy)