Rust a lot less than a sprinter
MK 5 2.5 DI Engine (quite noisy) but bullet proof, because of this are also abused to hell and back
With the TD. They are the first generation electronic "fly by wire" accelerator pedal and pump and have a bad reputation for failing (mostly unjustified). Make sure that the engine management light comes on with the ignition and goes out straightaway on start up and doesn't come on at all throughout the test run. You will need to give it a long run to make sure its right up to max operating temp. It should rev well without hesitation and without much smoke. While idling, any "hunting" does tend to point to injection system problems.
Get a good one, service it well, then learn to weld and you will never need another van
