CJs in '76 did have a heavy duty cooling package available, and it was available for a 258. Most base model Jeeps didn't have it and it doesn't look like yours did either. If your Jeep had A/C, it had the HD cooling system.
The heavy duty had a shroud, a three row radiator, fan clutch and a seven bladed fan.
The standard didn't have a shroud or fan clutch, a two row radiator and a four bladed fan.
Here is a link to the 1976 Jeep Technical Service Manual: http://oljeep.com/edge_76_tsm.html
Some guys put the Ford Contour electric fan in theirs. I have a base Jeep with the 258, run the stock cooling system and it sits at 190° all day long.