Barry,
When you get down to details like the Splinter Bulwarks used on ships, there can and is a great deal of variation. Each builder and repair yard had their own "styles" of doing things and that could vary at the same yard. Bristol (DD-453) and Ellyson (DD-454), as well as Hambleton (DD-455) and Rodman (DD-456), were delivered to the New York Navy Yard in a "transition" configuration ... between the pre-war and the new revised configuration. Bristol was completed by New York Navy Yard pretty much in the same configuration that the last of the pre-war Benson-Gleaves (DD421-444) were modified to just prior to the war. She had twelve 0.50-cal MG's and no 20-mm or 1.1-in. gun mounts along with four 5-in. mounts and one bank of TT. Ellyson and the others were modified to the new standard that was intended to accept eventually two twin 40-mm mounts. However, since the twin 40-mm mounts were not available until July 1942, Ellyson and 23 other Benson-Gleaves received the interim configuration of one quad 1.1-in. mount (on the starboard side) and a single 20-mm (on the portside) where the two twin 40-mm mounts would go. Ellyson was the first new construction Benson-Gleaves to receive the quad 1.1-in. mount. DD454-456 had their 02 level bridge squared off by the New York Navy Yard which conformed to the new standard design for the class. However, the next group of Federal built Gleaves class units, DD483-490, retained the earlier round-shape to the 02 level of the bridge as seen on Aaron Ward and Buchanan and were modified by Federal to the new standard BEFORE delivery to the Navy and the New York Navy Yard did only minor modifications. Aaron Ward and Buchanan were near twins ... near not identical ... and required removal of earlier structures and installation of new decks etc. The remaining units, DD485-490, were modified during construction before it had progressed too far. Bottom-line, there was a learning curve and several changes to "styles" resulted ... variation to splinter bulwarks, where the searchlight platform was located and how it was built, etc. ... were seen on these ships for reasons we may never know. As construction progressed, there were other adjustments to what was considered standard and the other builders had their own ways of doing things. Then once these ships went to other yards/theaters of operation ... near sisters could end up not looking anything alike.