Though there are many Amtrak models available on the market, there are also many others that can be kitbashed without too much difficulty. Here is a list of projects that involve modifying existing models to represent Amtrak prototypes. Most of these are ideas that I have had, but have not yet attempted myself. However, as with all my ideas, I have researched these ones. If you have notes to add, please let me know.
When I initially thought of this project several years ago, my version would have used an IHC/Rivarossi corrugated-side 10-6 sleeping car as a basis for this duplication of a prototype rebuild. However, that model is now hard to find thanks to the end of IHC and Rivarossi's alliance, and since Walthers has released a much more accurate version of the same car, there's now a better starting point for this conversion. Just make sure you obtain the Walthers model in Amtrak Phase II, III, or IV, because all other versions (including Amtrak Phase I and Undecorated) represent non-modernized cars, with different underbody and side skirt arrangements. If you think you can modify the car without too much damage to the factory paint, Walthers offers their 10-6 painted as a Dorm/Lounge.
When Amtrak began making their Heritage Dorm/Lounges, all they were doing was taking a 10-6 sleeper and blanking out a few windows, then remodeling the interior. Some of the 10-6s had blank letterboard areas while others had fluting there, depending on their ancestry as former Union Pacific or Santa Fe cars (thanks to Jeff Finch for bringing this to my attention). As a result, some Dorm/Lounges have the fluting and others don't. If the car you are modeling has the fluting, and you really want to include it on your model, I suggest you look at the Con-Cor 10-6. However, the Walthers 10-6 is a far better model to begin with, and it accurately represents blank-letterboard cars, so I recommend using that car. Either way, you will need to blank out the 5th and 6th windows, counting from left to right, on the right side of the car (vestibule to the right). On the other side, which has fewer windows, blank out the 3rd window from the right. The small train gif images below illustrate this:
The underframe as furnished with the Walthers car is correct for a Heritage 10-6. I'm not sure whether it stayed the same after conversion to a Dorm/Lounge, but I would assume so. To finish the car, paint the body a stainless steel color, or Flat Aluminum if you want to match the Walthers silver paint, and use Miscroscale's Phase IV Superliner decals for the striping and numbers. A few Dorm/Lounges had taller stripes, which can be represented by Microscale's Amfleet Phase IV set. Proper "AMTRAK" and car type lettering is not available in decal form, but the you may want to investigate dry transfers in the Helvetica typeface.
Amtrak's P32 may look at first glance to be nearly identical to the P40BH and P42DC diesels, but there are a number of important differences that set it off. First of all, it is a dual-mode engine, meaning that it can operate either as a normal diesel, or it can draw power from a third rail. It replaces the ancient ex-New Haven FL9s, which were a much older version of the same concept. Externally, the P32's radiator grilles (lower side at the rear of the locomotive) are taller and not as long as those on the P40/P42. The side access door and the grille above it are moved forward slightly, as is the exhaust stack on the roof. There is also an extra pair of grilles on the left side only, located at the top rear of the side. On the roof, the radiator fan is recessed more and covered by a pair of small radiator screens. The "fishbelly" portion of the underframe is shortened by a few feet at the rear to make room for another battery box. The trucks have third-rail pickup shoes. For some detailed photographs of the P32, visit my photo galleries. This project is something that I've always wanted to do, and now that I have an extra Athearn P40 model and a scrap shell to salvage extra grilles from, I plan to soon give it a try. It has been confusing, though, to figure out exactly which details must shift forward so that I can plan my saw cuts carefully.
Anyone interested in a simpler representation of the P32AC-DM should check out the April 2002 issue of Railroad Model Craftsman. There is an article by Frank Cicero that details a more basic conversion designed to give the impression of a P32 without requiring too much work.