[cleanspeed1]

Any mechanically injected diesel will work well, the electronic diesels that don't use a piezo style injector work well also.

The VW would be the cheapest with the best part support.

The Mercedes products are better, but start with a well maintained, rust free unit or it'll nickel and dime you to death. Don't worry about the miles, just do a pre purchase inspection, and as long as it passes, get it.

The VAG powered Volvos and Audis ( same as the VW, but in 5 and 6 cylinder versions ).

The turbo versions are not affected by altitude as much, the only thing that slows a turbo diesel down is some malfunction in the fuel system or the engine itself.