Gearbox swap

Hi all.
I have a slant 6 with three on the tree in my 65 A100.
I'm thinking of swapping the box for an auto, anyone done this?
Any advice, information, recommendations as to what box i should be looking for.
Thanks in advance.

if the engine is a /6 and it's staying then my help is limited ,
but the automatic tranny from a a100/08 are geting harder to find
and the / 6 automatic tranny's from a 1971 thru 78 will work but you will need the tranny cross member and drill out the frame and weld a selve in there, and a new drive shaft

I have found a 727 box, i just need to find out the date of my engine because it has been swapped at some point and also the age of the box to see if they are compatible