In 1947, the C&O ordered five additional and very similar locomotives, numbering them 310–314; these were class L-2-A and differed mostly in using Franklin RCpoppet valves instead of the Baker valve gear of the L-2s. These were the last express passenger steam locomotives ordered by a United States railroad, and some of the most expensive at $353,346 each, 80% more than the cost of the 8 earlier L-2 locomotives.[1]
Both classes were among the largest 4-6-4s ever built, and they were even more powerful than the C&O's L-1 class. The heaviest were the C&O'sL2a class at 443,000 lbs,[1] They were intended to work the C&O's top-flight express trains on level ground; the railroad purchased 4-8-4 "Greenbrier" types for mountain service.
By 1953, C&O passenger services were wholly dieselized, and there was no more work for these locomotives to do. Hudson locomotives were very unsuited to freight work, with such a comparatively small proportion of their weight on the drivers. All the L2’s and L2a’s were quickly scrapped by 1953.