Yes, it's not a straightforward question. Generally, as reps are becoming closer and closer to the gen in construction, the parts will become interchangeable with the gen, so theoretically they should also be interchangeable with each other. So the question is how old is your H-factory caseback? The V3/V4s are only a few years old so in order for the caseback to be compatible with the caseset, the model should have been released around a few years ago as well.