3:55 gears for 7 1/4 rear end non-sure grip

Application year makes a difference. I sold an early 3:55 gearset (removed from a '62 sbp rear) to someone who wanted to use them in a later bbp 7.25 rear. In trying to make things right I learned that later 7.25 rears used a larger diameter bolt to attach ring gear to the carrier assembly. Just a word of caution given many online sellers say a part fits but then it doesn't. Sorry I can't be more specific on years changes took place.