There were also two styles of Transfer Case body, in both single and two-speed cases. The style with a rounded bottom held the 2 pint capacity, while the flat-bottom case held 5 pints.
Oddly, the Ford Master Parts Catalog shows the rounded-bottom case (2 pint) being the 
EARLIER part number, while the flat bottom case (5 pint) has a 
LATER part number, opposite to what the operator manuals might indicate.
See pics in 
THIS THREAD.