Not that I want to throw gas on the fire, and I completely understand the arguments that Mongoose went and changed an iconic ship, but......
I was looking through the files from the CT CD and noticed that the only place the AHL deck plans are detailed is in
"CT G03 Game 03a Azhanti High Lightning Complete" (and two files split from this) and "CT 05 Supplement 05 Lightning Class Cruisers". The first of which is a ruleset for a miniatures game and the second a supplement for use with that game (at least based upon the title of the book). While the books do not have a complete deck plan of the entire ship, it does list them in such a way that you can (safely) assume that they were laid out like a building, with 84 decks.
Now perhaps I am being naive here, but isn't it possible that the detailed deck plans were organized like a "skyscraper" simply to make it easier to print and play the miniatures game? Otherwise the deck plans would be very large and, at that time, prohibitively expensive to print for a retail game.
The reason I mention this is that the other reference I found to AHL is in
"CT S09 Supplement 09 Fighting Ships" where on page 31 it clearly shows an image of a 60,000 ton "Frontier Cruiser" (which is identified as the AHL in the comments) flying "belly down", which would appear to support the layout that Mongoose published.
However, the bottom line is that, quite honestly, it doesn't really matter. We can use either layout, or even create our own. After all, it isn't the first time that a newer book has been published that has changed some previously published "fact", nor will it likely be the last.
Now I will take my 2cr, step tot the side, and keep my mouth shut.