Question about 7 1/4" rear end differences

Not too hard to figure out. As was said, the extra metal aids in cooling, shedding water AND also helps to dampen extra noise sometimes created by brakes like squealing and such. I would also make a guess that the extra weight could dampen vibration as well. @Charrlie_S is a wealth of knowledge on these little rear ends. Maybe he will chime in with some more info.