Between Pratt & Whitney and numerous licensed companies, there were over 180,000 of these engines manufactured in a number of specifications. The B-24 Liberator would have been their major recipient but other famous aircraft using the same engine were the Consolidated Catalina flying boat and the Douglas DC3/C47/Dakota. Refer Wikipedia link for other aircraft that used this engine.As a result of the significant and ongoing usage of these engines in civil aircraft such as the Douglas DC3, they are by no means rare. Many parts can still be sourced new and there are several companies that have the capacity to rebuild these engines to an airworthy standard.The Pratt & Whitney R 1830 is a double row 14 cylinder air cooled radial engine with a capacity of 1830 cubic inches (30 litres), developing some 1200 horsepower at a maximum 2700 rpm.radial engine, twin wasp, r1830