The frontera 2.8 is a tuned version of the trooper 2.8. Puts the same BHP but lower torque as the Isuzu 3.1, but with the benefits of direct over indirect injection.
The 2.3 is a bedford CF engine. I've known a few have oil pump failures though :(
The 2.2 dti has a diesel lubricated fuel pump, run it out of diesel and £600 bill for a new / reconned pump.
The 2.5 has a mechanical pump, not the electronic one. PITA when it goes wrong, but a fine engine when it's working.
muddyfrontera.co.uk for loads of decent technical information.