Thanks again Arnold for another great topic and for letting me know that none of my photos from my previous post ( now deleted ) did not show. Here is an abbreviated version of my previous ( now deleted ) post. I will post more when time permits.
As I model the Transition Era, I have many favorite diesel locomotives! The class one roads I model are B&O, Pennsy, Western Maryland, and Norfolk and Western since all of these roads owned trackage in my home state of Maryland during the transition era. In addition to these four class ones, I model 4 short line carriers which existed in Maryland during the Transition Era. Those roads are: Maryland & Pennsylvania, Baltimore & Annapolis, Canton Railroad, and Patapsco and Back Rivers. Additionally I allow myself to model the Washington Terminal Co., the company who operated Washington DC's Union Station from the origin of the station until the AMTRAK era.
One of my favorite diesels is the Rail Diesel Car also referred to as a RDC car and/or Budd car. WHY? - The sleek look appeals to my eye. I used to see these cars in commuter service in consists of one, two, or three in daily commuter service between Baltimore and Washington DC on the B&O's Washington Division. As the B&O is my favorite railroad the Lionel MPC era cars were a must for me to purchase for my layout. Many railroads purchased these cars to use in commuter operation and railroads used even them in longer distance trains too. The B&O ran a 3 car set between Philadelphia and Pittsburgh. The B&O purchased full coach RDC 1s and combination baggage /coaches RDC 2s. The prototype cars were built by the Budd Company. Each car was powered by two 275 horsepower diesel engines which totaled 550 hp per car. When accelerating a thick plume of black smoke would shoot upward from the domes of each are. 
MTH RailKing B&O dual purpose GP9. WHY? - I love this livery! When I was 11 years old I was given a cab ride in a GP9 that worked the B&O branch in my hometown. The engineer was impressed that I knew whistle signals so he let me blow the horn ( 2 longs a short and a long ) each time we crossed the grade as the locomotive was switching cars in out of a warehouse. If I were ever given an ultimatum of only keeping one diesel engine, my keeper would be this dual purpose GP9. Why? Because the GP 9 ( or entire GP series of locomotives for that matter ) could handle any job the railroad had .... Fast freights, way frieghts, yard switching, passenger trains of all varieties, even long distance passenger service. Because the air reservoir tanks are located on the roof some railroaders call the dual purpose GP type locomotive torpedo boats. GP 9s not equipped for dual purpose had their air tanks located under the frame of the locomotive near the fuel tank. Because passenger service required steam heating and therefore a steam generator, water for the steam generator was store in a tank alongside the fuel tank. The water tank displaced the air reservoir tanks. 
K lone F3 in B&O livery. 
Baldwin Shark Nose R-16 demonstrators. Why? - I love the stylish paint scheme which works well for Christmas time. I do run the shark demos year round too. 
EMD F3 with a K line body and MTH innards with PS3 in Reading livery. Why? - The detail on this locomotive is superb! Check out the rear view mirror! Reading Company works out fine in my layout scenario since the Reading had trackage rights over parts of the Western Maryland. Plus Reading and Western Maryland were part of the Alphabet Route famous for its' Alpha Jets fast freights which used pooled power. 
Washington Terminal Company RS1 number 63 with TMCC made by Atlas O. 
Why? - I love the look of the RS1 with the cab roof overhang. Traveling New York Ave. in out of DC almost on a daily basis for many years, I could not pass the Ivy City Engine Facility without straining my neck to see all the locomotives being serviced. I would often see number 63 on the service track, pulling a cut of passenger coaches, or just sitting in the yard. When I got the opportunity to purchase this engine, I jumped on chance! I also have the MTH RailKing version of Washington Terminal RS 1 number 46 with Proto 3, however I prefer the sound and operation of this Atlas O version. Arguably the RS1 was the first road diesel albeit a bit under powered for road work at 1000hp. A dual purpose locomotive, the RS1 worked well in coach yard, freight yard and passenger commuter operations of short trains. They had a long production run of almost two decades and were a good seller for ALCO.
