One other thing John, if you can get a pre-emissions tractor it would be a good thing in my opinion. Not sure how many years you have to go back, but I think about three.
If you look under the hood and there is a big stainless steel muffler looking contraption that has a Diesel line and electronic wires going to it, it has emmissions equipped.
On large farm tractors or over the road trucks these generally do not give lots of problems. But stop and go delivery trucks, utility type tractors that do not see a lot of full load action and other applications where the engine is not running at a good power level I see these as potentially problematic.
Under full load the engine runs pretty efficient and the particulate filter doesn't get plugged often. Under stop and go low temperature partial load applications the filter plugs up more often. Then the emmisions system goes into automatic regen mode where Diesel is injected into the unit, high temperatures are generated, and the particulate filter burns off the residue. This is all controlled by an onboard computer of course. To me it just looks like something to give trouble over time, particularly in a utility type application where 90% of the time the engine is operating under low partial loads.
I just bought our first such unit about a month ago (Versatile 500 tractor with 15L Cummins) so I have not had actual experience. But from what I have heard engines not used at higher load levels tend to give more problems than otherwise. The last two utility tractors I bought new actually were bought a year or two early just so I could avoid the next year model that had the emmision additions.
