Swapping a manual for me is easy LOL! I restore and modify a bunch of stuff...but I don't know diesels very well at all!
I'd be willing to do the work to swap it to a manual. I'm assuming the manual trannies are rare...would one from a 300 D bolt up to the 4 cyl or are they a completely different animal.

But what about more power from the engine? I also have been thinking about swapping the 5cyl into there. I think it requires moving the motor mounts around. But I'd like to get more power out of the 4 cyl if I can.

(I grew up with this car and it's been handed down to me so I can't get rid of it....it's special )