Can this be straightened and used???....

I for one do NOT understand how a gearbox can "look like that" and still be attached, in some way, to an engine!!!!

I can not see it either, I broke the input shaft off a 833 one time in an accident, bell housing broke in several pieces, but the shaft made a clean break.
Now it is my alignment shaft.

If the case is not broke, you might be able to fix it with a new front shaft and bearing retainer.
Those old trans are really tough.