Not sure how this thread swapped over from B-24 engines to Merlins? There were some 19 000 Liberators built, and around 13 000 C-47 Dakotas which means a total of 102 000 PWA R1830 engines fitted to new aircraft of these types alone. There were a total of 173 618 of these engines built and there are still a number of DC-3's flying, and both new and second-hand spares are freely available.