Sounds like you're confusing the Loco and the Dynamometer car used in the road tests, there are plenty of photos in existence of Deltic both as it was and as it is today. The link will take you to the oldest one on the Railway Forum gallery.:-
http://www.railwayforum.net/gallery/...&searchid=8993
And this to the most recent one.:-
http://www.railwayforum.net/gallery/...&searchid=8994
Regards, 62440.