There is another ship, from reality, that might bear looking at. The USS Constitution, currently in Boston, has been rebuilt roughly every 25 to 30 years and has had many different appearances. Yet through all that, her structure has remained the same. The current ship we see, still carries the original keel and lower section of all the ribs. This would be the same with the Enterprise when she went in for the TMP refit. She seems to have been stripped to her frame and rebuilt, yet the core of the Saucer, Dorsal, and Engineering sections are the same. The changes to Constitution over time relate to the above water structure. Initially, she had lower sides and had a figurehead. The masts and yards were change frequently and we have a couple of examples of what she looked like in the form of contemporary pictures and models. The earliest photo is from 1858 (oh, she was laid down in 1794 and launched in 1797) and shows the ship much as she is now. This was following her 2nd refit. Her third refit in 1874-78 resulted in many changes, including armament and the addition of a poop deck. When she was retired from active service very few years later, they built a barnlike structure over the decks and minimized the masts. In 1907, when she should have had a refit (oak hull planks only last so long), she at least had the barn removed and was restored to look most like her original self (except the bow). Then her fourth refit, and most major, resulted in her looking like the oldest photo from 1858. Her next refit in 1960 was just to replace the oak. In 1975 her bow was modified to be more like her fighting prime. In 1995 the refit again was just to replace the oak. If you compare this to the Enterprise, the engines were modified a couple of time, the sensor dish was changed, the bridge replaced, She served several possible five year missions. Then Kirk and crew abused her for 5 years and and Starfleet authorized a major refit. This would be the equivalent of the Constitution's first refit, tripped down and rebuilt. The cosmetic changes would be like the Constitution's many changes to her rigging and figurehead. Like Enterprise, Constitution was one of a class. There were three, the United State, Constituion, and President. No two were completely identical. A similar thing happened in the 1960's with the Kitty Hawk class of carriers and again with the Nimitz class. No two of either class are quite the same. For a time the John F Kennedy was considered by some to be a seperate class, but officially she was a Kitty Hawk class carrier. That leads me to Enterprise (and Ill have to refer to her by her number to avoid confusion) CVN-65. The carrier had many issues during construction that resulted in a different design for the tower than on any other carrier. In the early 90's the tower was modified, a cosmetic change on par with the Starship's many changes prior to the TMP refit. The Navy's Serivice Life Extension Program refit on Enterprise entailed many major changes to the interior. The watertight doors were changed to be flush with the floor instead of having to step over the high sill. 6 of the 8 reactors were removed (because they found that they only needed two). And I just have to mention as a sideline that the two US Navy ships I have brought up, Constitution and Enterprise, are the Navy's two oldest commissioned ships at the moment. Enterprise will be over 50 when she is retired in a few years. Constitution is over 200. So when we encounter differences in ship designs in Star Trek, it is something that should be considered normal for a Navy. Things wear out and need to be replaced. New technology superceeds the old and upgrades are needed. While what we really see is just a redesign of the sets and models, it fits nicely with the now established time-line (which is fairly consistant even with some possible variations) and with typical naval practice. If we can assume that 23rd century shipbuilding is as modular as Sternback stated that 24th century was, then the drastic change of appearace of the Enteprise for the TMP refit makes much more sense. I'd also like to point out that the TMP Enterprise has the same teardrop shaped platform under the bridge as the TOS Enterprise. The versions of the Constituion class we have seen in various stages also does not include the original. Our first view of the Enterprise is when she is 8 years old and we never see Constitution. Were they identical or were there some differences. Who knows. Then we have the Cage and the two Enterprise models. I tend to discount the 33 inch model as it was barely used and has some drastic differences from what the 11 foot model looked like. For the Cage, though, the stern view shows the end cap of the warp nacelle and the impuse engines, which are different from what we see in WNMHGB. Then of course are the modifications for WNMHGB and the regular production. Then, we have Constellation. We all know it is the AMT model kit, but it follows the drawings of MJ and FJ. I would consider this the Bonhomme Richard sub-class redesign. Then we have FJ's plan. Then the Phase II Enterprise, then the pre-production movie Enterprise, then the final Movie Enterprise. That makes a possible 8 variations of the Constituion Class that we know about, plus a couple of others that have been suggested. The Technical Manual lists lots of ships and they, unfortunately, don't match the names we hear in the series. However, I again turn to the US Navy to point out that what gets authorized intitially may not match what gets built. The Navy's first carrier's were not born as carrrier's. The Langly was a coal tender. The first ship finished as a carrier, the Lexington, was not designed as a carrier. The class was originally to be the Constitution Class Battlecruiser. Somewhere burried in my papers, I have a list of the original names of the six ships. But plans changed. There was resistance to stealing the name of Constitution from Old Ironsides and the class was changed to Lexington with a possible Constitution later. Three ships were started as Battlecruisers, Lexington, Constellation, and Saratoga. Lexington and Saratoga were the furthest along when the design of the Battlecruiser was scrapped and the two ships were redesigned as Carriers (incidently the fastest two until post WWII). So if FJ had been writing about ship's authorized in the 1920's, he would have gotten the names and types all wrong. Similarly, he lists the authorization's for the five classes of ship in the Technical manual. I don't follow that the names and numbers went as listed. Evidence from production indicates that the NCC numbers varied and FJ does not list the Defiant. From my study of the US Navy and how it can apply to Starfleet, nothing can be taken as set in stone when dealing with authorizations and what happens in the end. That leaves FJ's Plans and Technical Manual a proper place in Trek without it ever contradicting what we see. The way I see it, the more confusing it is the more realistic it is.