Arnold DesJardins stands in the knee-deep hay under the goal posts in the south end zone in early December 1961. The hay was put on the field to preserve it for a month before the NFL championship game, which was played on Dec. 31.
According to Kickology:The Study Of All Things Kicker Related, The NFL standardized on the classic H-Style offset goalpost in 1966, but then went to the current slingshot goalposts in 1967. In 1974 they moved them from the goal line to the end line.
Since they were only standard for the 1966 season, it was difficult to find even these three photos. If you come across another, I'd appreciate it if you'd list it in the comments.