Changing Auto to Manuel

Currently running a 3.9v8 efi engine on a zf auto gearbox out of a disco. Now having a auto is nice and everything but I just can’t seem to get on with it on and off road. I’m thinking of putting a r380 gear box in and getting rid of the auto. Would this be possible or would I have to make a adapter plate? Also changing the gear box would I have to alter the engine mounts? Or would a earlier lt85 gear box bolt on easier?

buy a v8 r380,and it just bolts on,