Re: Can this be prevented? (Cracked case 700R4)
Newton's Third Law - for every action, there is a reaction.
As torque is applied, and lots of it, ie, 496 CID and a 3.06:1 first gear ratio, to move the heavy weight, the car, the engine/trans is twisting in the frame in the opposite direction.
The trans housing, being the weaker part, gave it up.
Think about it, the absortion/transfer points of the reaction are the engine mounts and trans mount, quite the long lever for the trans mount.
This why most operators installed a turnbuckle/torque strap from the front drvr side cylinder head to the frame/upper control arm shaft, or, old school trick, install drvr side solid engine mount only.
As Derek suggests, consider a midplate, or my suggestion an anti-torque strap from the block/trans bellhousing bolts to the frame?
Give a man a rescued dog for the health of both their souls.
'With age comes wisdom, but then wisdom ages you even more.'Other Stuff' GO CUBS!