Avery,
You know that there were twenty "Square-Bridge" GLEAVES class destroyers built to two slightly different configurations: Sixteen to the original layout similar to the basic repeat GLEAVES and Four (DD645-648) to a revised layout with staggered 20-mm and 40-mm mounts. Federal-built six units to the initial configuration (labeled as G-IIIA below) and the four revised configuration units (labeled as G-IIIB). SeaTac-built ten units to the initial configuration. All of the initial configuration built by both builders were "basically" the same WHEN BUILT AND DELIVERED.
The six Federal-built units built to the initial configuration (DD618-623) were delivered in the same aft deckhouse configuration as seen in the photo of DAVISON, except that when initially delivered, they all had only four 20-mm guns installed (two before the bridge and two amidships just forward of the aft deckhouse). Not too long afterwards, they had three additional 20-mm guns installed as seen in the DAVISON image (one before the bridge on an elevated platfrom and the amidships 20-mm guns were put into pairs port and starboard). HOWEVER, EDWARDS (DD-619) had an unique configuration when she was updated with the additional three 20-mm guns at Puget Sound Navy Yard ... different than the other units all stationed on the East Coast. The first two units (DD493-494) built at SeaTac, at least, were delivered in basically the same configuration as the Federal-built first configuration units (DD618-623), however the remaining units (DD495-497 and 624-628) had a revised aft deckhouse bulwark for the twin 40-mm mounts and Mk 49/Mk 51 directors. These SeaTac-built units also were up gunned ... some of the last built units may have been delivered with seven 20-mm (photos are lacking) to seven 20-mm guns.
However, after service, changes in configuration between units occurred. At least two units had HF/DF antennas installed in place of their SC radar for a period of time. ASW Mousetrap was installed on some units as well.
DD-618 Davison G-IIIA Federal 11-Sep-42
DD-619 Edwards G-IIIA Federal 18-Sep-42
DD-620 Glennon G-IIIA Federal 8-Oct-42
DD-621 Jeffers G-IIIA Federal 5-Nov-42
DD-622 Maddox G-IIIA Federal 31-Oct-42
DD-623 Nelson G-IIIA Federal 26-Nov-42
DD-645 Stevenson G-IIIB Federal 15-Dec-42
DD-646 Stockton G-IIIB Federal 11-Jan-43
DD-647 Thorn G-IIIB Federal 1-Apr-43
DD-648 Turner G-IIIB Federal 16-Apr-43
DD-493 Carmick G-IIIA SeaTac 28-Dec-42
DD-494 Doyle G-IIIA SeaTac 27-Jan-43
DD-495 Endicott G-IIIA SeaTac 25-Feb-43
DD-496 McCook G-IIIA SeaTac 15-Mar-43
DD-497 Frankford G-IIIA SeaTac 31-Mar-43
DD-624 Baldwin G-IIIA SeaTac 30-Apr-43
DD-625 Harding G-IIIA SeaTac 25-May-43
DD-626 Satterlee G-IIIA SeaTac 1-Jul-43
DD-627 Thompson G-IIIA SeaTac 10-Jul-43
DD-628 Welles G-IIIA SeaTac 16-Aug-43
EDWARDS (DD-619) in about December 1943 showing the unique 20-mm bulwarks amidships.
MADDOX (DD-622) on 17 Novemebr 1942 a couple of weeks after commissioning showing the original delivery configuration.
HARDING (DD-625) on 6 December 1943 showing the configuration with seven 20-mm and equipped with an HF/DF array.
THORN (DD-647) on 28 May 1943 showing the staggered twin 40-mm and two 20-mm configuration.
