Douglas,
The Reading 3000-series K1 started as a rebuilding program in 1927 with parts supplied by Baldwin. The first 11 locomotives were rebuilt in the Reading Shops from N1’s 2-8-8-2 which were built between 1917-1919. An additional ten locomotives (3011-3020) were built by Baldwin. The 3000-3009 were classed K1-sa, 3010 was classed K1-sc, and the 3011-3020 were classed K1-sb.
The big difference between the rebuilt locomotives and the Baldwin built locomotives were the number of sand domes. The rebuilt locomotives kept their twin domes from the N-1's and the baldwin built locomotives had one large dome.
The 3010 was classed K1-sc because it was built with Caprotti valve gear. This proved to be troublesome to operate and costly to maintain. In 1942 it was replaced with the same Walscheart valve gear the others locomotives had and the 3010 was re-classed as K1-sa.
In 1945 while the Reading shops were busy building the T1 4-8-4’s the K1received some modernization changes including dynamically cross-balanced Baldwin disc main driving wheels, tapered main rods and high speed drifting valves. These changes where made to increase the K1’s potential speed from 50 to 60 m.p.h. making them similar to the new T-1’s. The locomotives were re-classed from K1-sa/b to K1-sd/e.
The class survived intact until the first end of steam on the Reading in the beginning of 1954. The rebuilt K1’s were first to be retired in May of 1954. Followed by the Baldwin built locomotives in March of 1955. There were no survivors.
The tenders are similar in size and construction to the T-1's tender but yet it is different in a few ways. First the tender trucks are both 3 axles but the T-1 used roller bearings and the K1 used solid bearings. The side of the tender at the coal area is also different. On the K1 the are straight with a slight radius at the top well above the line of the cab roof. On the t1 they curve starts lower and is more rounded closer to being in line with the cab roof.
First one of the rebuilt locomotives:
Next is one of the Baldwin built locomotives.