: Lists of components, such as rocker box covers or internal engine "pieces" that cover specific assemblies of the 755-series radial engines.
RAR files are compressed archives, often used for distributing large technical manuals or software. If you are looking for this specific file, it typically contains one of the following: 755.rar
Based on the technical context of the query, it is likely that "piece covering 755" refers to a specific manual or part related to the (or Lycoming R-755) radial engine. : Lists of components, such as rocker box