I tried to obtain technical information on current models from both Ford and VW a few years ago and they were both utterly useless. Not sure whether they'd be any better with an older model, or if they even know the Mk2 existed...
You've got nothing to lose by asking them though. (Except the cost of the call, your time, and the will to live when they come back with a generic nonsensical answer that's completely irrelevant to your query. )
I suspect they'll just check the same parts catalogues that we can check through catcar & 7zap. Unfortunately, the catalogues are contradictory - I've seen reference to 3 different types of nut used with different models on the 5 spoke steels, although interestingly, can't find any of them using the 2 piece nuts.