After completing the center deckhouse, I moved on to the after superstructure.  After adding various details and photoetch parts, the completed assembly looked as shown in the photo below.

While I was pretty happy with the project overall, the more I looked at the details, the more disenchanted I became with how certain things looked.  For example, the aft Mk37 director sat too low when compared to the top of turret #3; the basic structure of the kit-supplied parts was of poor overall quality, etc.  So one evening I sat down with my CAD program and started tinkering with the idea of a completely scratch-built aft superstructure (note: the aft stack looks pretty good, so I decided to incorporate it into the new design).  This version would incorporate the center deckhouse theme into a fully integrated structure, and would blend seamlessly with the existing forward deckhouse, the result being a more monolithic superstructure.

Of course, each time I add my own design elements to this model it lessens the "accuracy," but it's pretty hard to call a model of a ship which was never built "inaccurate."  One of the beauties of building Montana :).

At any rate, here is the result of this work.  This design incorporates a brutal SIXTEEN quad-40mm gun tubs arranged in a rearward-cascading pattern.  I was after maximum density while retaining a reasonable field of fire for each emplacement.  I also managed to squeeze in four 20mm galleries, two each forward and aft of the aft stack.  Additionally I raised the after platform one deck, correcting the issue with the after Mk37 director.

All is happy in Montana... or so I thought.  I immediately went to work printing patterns and cutting plastic... 

Since some people have asked, the way I use to cut fairly intricate parts from sheet stock is as follows:
1. Print the desired pattern and cut it out, leaving a 1/2" (approx.) border around all cut lines.
2. Tape the pattern to the sheet plastic, being sure to tape all the way around the perimeter.
3. Cut the part using my dremel 16" variable speed (electronically controlled) jig saw.

If you have the saw set up correctly, are using the correct blade, and have a little experience, you will find that you can obtain very accurate cuts by hand, even in this scale.  Here are the major components used to create the after superstructure.

Of course, it is very important to ensure everything is square and plumb during the construction process, especially in such a small scale, as even slight errors accumulate into fairly massive scale alignment problems.

Here's another picture, taken after completion of additional construction.  At this point the 02 and 03 decks are built up, and 04 is in process.  You can see that the new aft fire control tower is integrated into the deckhouse - no seams to clean up!  Also, you will note that on the 03 deck there is a weatherdeck passageway forward of the FCT, allowing crew to transit between port/starboard gun tubs without having to open hatches, etc.

Note the use of Tom's Modelworks hatches.  THEY ARE FABULOUS.  Finally, the curved notch at the front end of the 03 deck is intended to fit around the forward stack when the fore/aft superstructures are mated together.

This photo shows how I handled the cantilevered 40mm gun tubs.  A simple framework was constructed beneath each one, and then this was covered with .005" sheet styrene, yielding a nice, clean look.

The sequence of images below shows various views of the finished (?) rear deckhouse mocked-up with the revised forward house.