The new locomotives became the M1a class and had a longer wheelbase than the M1's due to the addition of the Worthington feedwater heater. They also received new larger tenders, class 210F75, which became known as the coast-to-coast tenders. The first 50 M1a locomotives, #6700 - 6749, were built by Baldwin. The Juniata Shops, which became knows as the "Altoona Works, " built the next 25 M1a's numbered 6750 - 6774, and the remaining 25 M1a's were built by Lima and were numbered 6775 - 6799. Starting in 1946, 41 of the M1as received further improvements by increasing the boiler pressure and adding circulators to the firebox.
The improved M1as became the M1b class. The best way to tell them apart is to look for the circulators on the firebox just above the running boards. The circulators are those round objects in a diagonal line that look like wash-out plugs.
The PRR M1a/bs were considered to be the finest of the PRR's steam locomotives. And in the end, they even hauled the heavy ore trains, which there were not originally intended to pull. They did it all in style! When moving forward from a stopped position, toots twice.Thanks for your interest in our products. The item "BROADWAY LIMITED 3642 N M1b 4-8-2 PPR 6755 Strasburg Museum Paragon3Sound/DC/DCC" is in sale since Tuesday, June 12, 2018. This item is in the category "Toys & Hobbies\Model Railroads & Trains\N Scale\Locomotives". The seller is "greatdeals4uonline" and is located in Venice, Florida. This item can be shipped to United States, Canada, United Kingdom, Denmark, Romania, Slovakia, Bulgaria, Czech republic, Finland, Hungary, Latvia, Lithuania, Malta, Estonia, Australia, Greece, Portugal, Cyprus, Slovenia, Japan, China, Sweden, South Korea, Indonesia, Taiwan, South africa, Thailand, Belgium, France, Hong Kong, Ireland, Netherlands, Poland, Spain, Italy, Germany, Austria, Israel, Mexico, New Zealand, Philippines, Singapore, Switzerland, Norway, Saudi arabia, Ukraine, United arab emirates, Qatar, Kuwait, Bahrain, Croatia, Malaysia, Brazil, Chile, Colombia, Costa rica, Panama, Trinidad and tobago, Guatemala, Honduras, Jamaica.