Volvo Penta Engine Part Catalog - volvopentastore -B is the second version, etc.. There is no link between the suffix and production years. All engines with -A were not built the same year. A 5-B and a 5-B are not similar. A 4-D is newer than and different from a 4-C. The second letter, if present is always an F, it notes that the engine is freshwater cooled.