Re: What's the difference between the "JTD Multijet Diesel" and the "JTD Diesel"
the 2.4JTD is the same as the engine used in the mk1 fiat marea. that means spares are very easy to come by in scrapyards and this engine has been proven to be very reliable and tuneable. the JTDm was the second generation of the JTD, there were many changes to the head, not least twice as many valves. you get more power and torque, but for some reason the fuel economy didnt improve and reliability seems to have suffered slightly.
personally i cant see the point of the 2.4JTD (neither could fiat or GM- they favor the 1.9) because the 2.4 is heavy which upsets the balance of any car, and for its size the output and economy is not great. that is why the 1.9 is a good choice if you care about handling and runnig costs. you can tune the 1.9 to give very similar output to the 2.4 so there is no real benefit to having the extra weight up front. the only real difference between the 1.9 and 2.4 is an extra cylinder.
personally if i had the choice of any JTD, it would be the 1.9JTDm remapped to 200bhp and 300lb/ft, coupled to the 6speed box.