From "The Legionnaires Who Never Were", Action Comics #392, September 1970. Cary Bates, writer, and Win Mortimer, penciller.
There's a plot which explains why we're seeing "male versions" of Saturn Girl and Princess Projectra but who cares about that? The real reason to read this story is seeing these costumes! On MEN! Note that this is the first appearance of Saturn Girl's new costume design, which was submitted by a reader.
Click for larger images.
I can't decide if the men look really hot or really stupid. But aren't those thigh-high boots on Saturn Lad to die for? Honestly, more male superheroes should wear them. I also love the opera gloves on Prince Projectur.
Not to spoil the plot too much for you, but Saturn Lad is really Sun Boy, and the Prince is Brainy.
Really, the plot for this story (something about fucking with Projectra's mind to see if she would snap under pressure - it doesn't make any sense and I'm not going to waste time trying to explain it) is so thin that you can see through it. I suspect the only reason they published it was to show the men in women's costumes. Cary Bates, did this fulfill some personal fantasy for you?
Anyway, I thought it was a nice addition to the current ripping on Wizard's imbecilic drawing guides.
Saturn Girl's old costume was better.