One other thing nobody has mentioned yet. The VW diesels up to 1980 were 1.5L. From 1981-up they are 1.6L, and from 1984 (or 1985?) up they have hydraulic valve lifters so you don't need to dink with valve adjustments. The difference between the 1.5L and 1.6L is HUGE. Although the horsepower rating is only 10% more, the torque rating is something like 30-40% more. I have driven both and would never buy a 1.5L on purpose, they are beyond gutless, even at sea level. I can't even imagine trying to drive one at 5000+ ft elevation! A 1.6 is a decent engine, though, particularly with the hydraulic lifters. MPG figures between 40-55mpg are possible, typically mid-40's. If cared for these should last 300-500kmi. As usual, take care of the cooling system, and replace the timing BELT (not chain!) every 50-75kmi.
Note: I've owned 5 diesel Dashers, and still have one with a 1.5L engine that was supposed to be a 1.6L... long story...
HTH,