I'll go out on a limb here and say it's a late production "Mark Series" CTC-7. "The Meredith."
The CTC-9 sets did not use 5U4's.
Courtesy Ed Reitan's site:
CTC-7_Meredith300.gif
Address:
http://www.novia.net/~ereitan/Galler...eredith300.gif
-Steve D.