What manned Mars craft was concelled? Saturn V could be cancelled because in was part of a physical program had a production line...viewgraphs can't be cancelled there not programs!

Anyway is this what you are writing about?

North American Rockwell (NAR), the Apollo Command Module (CM) prime contractor, performed this study of a Mars Excursion Module (MEM) lander for NASA's Manned Spacecraft Center in Houston, Texas between October 1966 and August 1967. NAR proposes a 30-foot-diameter, CM-shaped (conical) lander [view]. The lightest design (65,800 pounds) carries only enough life support consumables to support 2 men on Mars for 4 days and operates from a mother ship in low circular Mars orbit. Heaviest (108,990 pounds) is a 4-man, 30-day MEM that operates from a mother ship in elliptical orbit. A 4-man, 30-day MEM operating from low circular orbit weighs 75,200 pounds, while a 2-man, 4-day MEM operating from elliptical Mars orbit weighs 88,500 pounds. Typical MEM operations at Mars occur as follows [view]: