This is a pretty big question depending on how far you are wanting to go back. A few from the top of my head:
Western Allegheny rostered a number of 2-8-0's of PRR heritage.
The Susquehanna & New York (Towanda-Williamsport, PA) had at least two-a 4-4-0 and a 2-8-0.
The Sheffield and Tionesta (Warren & Forest Counties, PA) also had an ex-PRR loco used in construction of the line.
The Washington, Brandywine & Point Lookout in Maryland rostered an ex-PRR 4-4-0.
The Pittsburg, Shawmut & Northern also had an ex-PRR 4-6-0 (PS&N #3, IIRC) used in construction of the line.
The Washington (DC) Terminal also had a number of PRR locos lettered WT.
Art Audley, AA3RT
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