I have heard from two different sources that late in their production run, the SD heads and intake manifold were changed so the intake runners were individual and not in the head as in earlier engines. I have never seen this, though there are 5 different SD engines around here in various states of condition.
This really intrigues me, it seemed unlikely to me that Ford would go to the expense of such a change with diesel surely closing the door on the big gas burners. Thought I knew something about the SD's.
Can someone shed some detail on this? A photo would be wonderful!