There's a few things in there that make me believe min is in fact a oetinger.
The one picture on links above has the gt badge same as mine,
Gear ratios sound about right they are deff longer to those I remember my other mk2s having
She has a different engine noise to that of my other k jet mk2s more metallically as described in links above.
Really want to get hold of the previous owner as the guy I bought it off had bought it of a vw specialist who had obtained it from a vw technician who had owned it for 10+ years and most of info I'm getting ATM is third hand there was talk of options and he regretted not having the more aggressive cam and going for the milder option

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Another thing I noticed on the link you posted above is reg plate the oak Green is f 151 mine is f161 this might be a coincidence but are the other 121-131-141 ect?