[Kevin Thorp]

What you're talking about is a single acting cylinder. Unfortunately this type is typically only available in short strokes. The internal spring needs to be approx. 2X the stroke length, so it isn't practical for longer cylinders.

You could simulate a single acting cylinder by leaving the air fitting off the nose end of a double-acting cylinder and using an external spring or elastic to retract your piston. Be careful not to side-load the piston rod, especially when fully extended. That's when it's most vulnerable to damage.