I believe, and this is what I am unsure about, that the 2 seat sides has only 1 unit in between both seats. Unfortuantely, I don't sit back there all the time.
The seat maps on delta don't show the Empower units, unlike the seat maps on AA.
Sorry I couldn't be more helpful than my original answer which came directly from my contact inside Delta. If I find out more, I'll let you know. I've only flown F on the 764.