mdvineng said:
changing down at high speed will certainly wreck it sooner than later (possibly shattering the housing).
Most likely rip the mountings off.
Every auto I've had a manual to suggested that it could be rammed from D to 1 at 100mph if you wanted*, it will not go down to 1 until the roadspeed is low enough for 1 to engage, but when it does it will pop your eyeballs out of their sockets.
Also, the shock will likely break the one way clutch in the torque converter
*I never wanted to
I never mess with the gearlever unless it is to go backwards, or operate the transfer gearbox on a RangeRover
Incidentally, I rode motor bikes for 20 years before I discovered what a slipper clutch was
(the clutch drum is split in half, with a roller clutch that locks up when the engine is driving, and is free when the gearbox drives the engine, between the halves. In go mode, all of the clutch drives the back wheel. When changing down, the half clutch is weak, and will slip rather than lock the back wheel, or over rev the engine if you get too enthusiastic with the left foot)