Back2Fronts is an extensive mod that will overhaul your Call of Duty 2 game to a next level. This mod brings more variety, intensity, realism and battle-like experience. Try new weapons, fight new enemies, fulfil new missions and explore new options. Mod is SP and MP friendly (although primary part is SP).
PPS42 has got completely remodelled and a PPS43 was created as well.
What's the dif between 42, and 43?
If I'm not mistaken it had 20mm longer barrel (PPS-42), other than that differences were in production process.
differently shaped safety, different pistol grip, different production process.
See this screenshot: Moddb.com
PPS43 is available only from weapon selection menu. Russian soldiers don't use it.