I second Thrashingcow's comments;
You will also need a different engine support crossmember and the front frame crossmember where the front end of the leaf spring anchors. You will need to drill the frame to use the rear spring hangers.
I did this conversion, because of an accident and frame damage to my original '92 4x4, so I essentially had two complete trucks to start with. Concurrent with that project, my brother & I also converted his '86 D-250 gasser to a diesel using many of the 2wd components from my 2wd CTD.
It's do-able, but it is a lot of work.
Jack Dancoe