The N/A's were phased out in1991 when Fenders were fitted with the 200TDi, which were superceded in1994 when along came the 300TDi, so I think that someone has already swapped the injun over for a N/A.
Why?
My 1989 110 N/A runs perfectly, the emissions are much lower than many newer cars and vans, she will sit at 70mph + on the motorway all day without missing a beat!
The only 'downside' if you can call it that, is that the acceleration is not as nippy as one with a turbo!
0-60 in less than 3 weeks
However, if you are changing, let me know where you are and what you want for your N/A engine.