The Pennsylvania Railroad's class L2s was a class of USRA Light Mikados originally purchased (1919) for the subsidiary Grand Rapids and Indiana Railroad, and later rebuilt to Pennsylvania Railroad specifications.
After World War II, the Pennsylvania Railroad needed a lighter 2-8-2 type steam locomotive to handle lighter freight trains on the system, especially after World War II. So, the Pennsylvania Railroad decided to get steam locomotives from the United States Railroad Administration. The L2s were in their later years, rebuilt to specifications that the Pennsylvania Railroad used on all its freight steam locomotives. (High headlamp, oval numberplate and Belpaire firebox.) After these rebuilds they looked like the Pennsylvania Railroads class L1s 2-8-2s.
As heavier trains on the Pennsylvania Railroad became a reality, the Pennsylvania Railroad needed a heavier steam locomotive to handle a freight train on the system, so the L2s was demoted to smaller services and eventually retirement, when engines like the J1 and in later years, diesels replaced them too.