It might be interesting to note that the total production of E8's favored A units over B units almost 10 to 1.
http://www.american-rails.com/emd-e8.html
By the time production had ended on the locomotive in early 1954, EMD had sold 449 A units and 46 B units ...
And for E7's:
EMD ... sold some 428 E7As and 82 E7Bs by the time production had ended in the spring of 1949.