@GG1 4877 posted:KCS did modify the side panels on both their E6s and E7s after delivery by EMD. There are photos of both with the original square windows.
Modifications to the side panels of E and F units was pretty common in general. L&N did a similar modification to their E6 as well as add additional ventilation where windows used to be. Southern also similarly modified side panels to replace windows with ventilation louvers.
It was fairly common practice later in life on E8s and E9s to blank the porthole windows all together.
Did KCS buy any E7s new, or did they only have the ones they purchased from MEC? There's the b&w shot of KCS #12 with standard rectangular windows, but several color shots showing #12 with the round portholes). There are some snaps of MEC E7s being scrapped and there's a small square window unit next to a standard rectangular window unit (not a round porthole in sight). Did MEC buy any E7s with round portholes? E7s seem to be the most modified of the E unit family (Pennsy had so many modified E7s it would drive rivet counters crazy).
