7 1/4 Why is it so weak?

I've got a pile of 7-1/4 rears which I have ripped the pinion crossshafts right out of the carrier assy.and then trashed everything else. The design is just too small and weak to hold up to any power, including stock 273's. I do have a 7-1/4 Sure Grip in a 64 Barrucuda that has lasted since the car was new, and held up to a little mild punishment, but I'm guessing they are harder to find than a reasonably price 8-3/4 and for sure an 8-1/4. I recommend an upgrade to at least an 8-1/4 or just wait (probably won't be long) until the 7-1/4 fails having a plan in place for a replacement.