The 4HP24 comes in two versions, early and late. The early ones are about 15mm longer than the 4HP22 and can be made to fit but it is a lot of hassle.
The later 4HP24 auto boxes, known as an 065 box, are a straight swap into the diesel; just use the original diesel bellhousing, torque converter and diesel auto ECU.
The later ones can be identified by looking at the gearbox plate. It will say something like 030-065.
Question DAVE, looking at photos of boxes on ebay I assume the diesel torque converter is smaller in diameter than the petrol, is that why you say to change it?... Also from what year do you mean later.
scroll down the page and you will see them side by side.
You can get an uprated diesel torque converter but they are expensive and not worth it unless your engine has been chipped.
I am not sure what year the 4HP24 versions changed but I think it was 1997.
If you are buying one on ebay ask the seller to tell you what the number on the box is before you buy it. You want an 065 box.It is on a metal plate on side of the box near the XY switch.
Changing the box over is straightforward. All the bolts line up. I fitted a HP24 to my diesel over 5 years ago and it has been problem free.