Transfer case/tranny questions

[myname]

I have a 205 transfer case and a turbo 400 transmission. The piece that links the two is cracked in a couple places and leaking. I have been looking locally for a new one, but I am not sure what will interchange. Will one between a 350 trans and 205 transfer case work? Will one out of a 78' chevy work in my 72'? I have been told they are hard to find for automatic transmissions. Is there an aftermarket place I can find one if I don't find a used one? Thanks for any helpfull input!