The original type are the conventional curved-down cross-tubes. The later style have upward-curving cross-tubes with vertical skid support posts. The later style are designed for air-portability, as the vertical posts allow the aircraft to be lowered about 1.5 feet for loading onto cargo aircraft.
Follow the link to a pic of folded and dropped OH-58Ds.
http://regiment.home.mindspring.com/folded.jpg
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