Bruce,
These two websites have lots of pictures of D&H RS2s and 3s. It's hard to find overhead shots but there are pictures of the no.2 end to get an idea. D&H in Color Volume 1 and Trackside in the Albany, NY Gateway (both Morning Sun Books) have some decent pictures.
http://www.bridge-line.org/blhs/dhdieselroster.html" onclick="window.open(this.href);return false;
http://www.rr-fallenflags.org/dh/dh-loco.html" onclick="window.open(this.href);return false;
What are era you modeling? The boiler equipped RS2s, as delivered, had the stack centered on the rear hood, right up against the cab. The housings were tapered or slanted into the roof of the hood. This was common at least among eastern roads. The NY Central's and the New Haven's RS2s had the stacks in the same location.
After going in for rebuilds (not sure if they were truly rebuilt but they came out looking like RS3s, one telling feature being the battery boxes were moved from under the frame to the walkway on the no.2 end), I've seen stacks on these RS2s that are oval shaped or square and they're further back on the rear hood. Like this:
http://www.rr-fallenflags.org/dh/dh4005o.jpg" onclick="window.open(this.href);return false;
Then there are the two passenger RS3s that the D&H got from the B&M. They had tall round stacks.
http://www.bridge-line.org/blhs/images/ ... hl4082.jpg" onclick="window.open(this.href);return false;
