Diesels came with either a manual gearbox or an auto box. The cooler for the manual box was integrated into a section of the radiator near the bottom. The cooler for auto box models is under the LHS front wing. I think the very, very early ones (1995/96?) had no cooler under the wing. The gearbox does clearly overheat and later models ... from 1999 I think, then also had a fan fitted.
Engine oil coolers are separate and situated behind the radiator along with the turbo intercooler.
I am not aware there is an early and late radiator for the diesel. I think it is just two different types i.e. manual and auto.
The diesel radiator water connections, in and out, are all at the top unlike the petrol rads.
Aftermarket rads for the diesel now all seem to be for the manual gearbox car. These can be fitted to the auto box cars but the section for the gearbox is just left unconnected. That is probably what you can see.
I have actually got an alloy rad on mine and has been left disconnected. Been like that for 10 years+.
Not sure about OEM rads, whether they still do both types.