7 1/4 why weak?

I broke a 3.55 7.25 SG with a 340 and 10 inch wide tires, but it took a neutral drop coasting backwards out of a driveway to do it. From what I could tell after popping the cover off was the pinion broke a bunch of teeth off and the ring gear busted a couple too. Spider gears...no comment as I had seen enough. I replaced it with a 2.76 peg legger (only one I could find over that weekend) and that car was never the same. You can break them, but it takes some dumb driving or some power to do it, or you can just get a weak one.