I was piecing together the LE6940FDE upper receiver that I have when I ran into a difference with the upper receiver that I had never noticed before.

In the attached photos I have circled in green the part differences that I am referring too.

The retention of the ejection port cover rod on a 6940 upper receiver is completely different than it is on a standard, non-modular, upper receiver (LE6920 or CR6920 for example).

I had never noticed that before. Now I need to identify the roll pin size and order a few so that I can install the ejection port cover on this 6940FDE upper receiver.