Not sure how relevant this info is concerning modern 3-point belts, but it may be useful in some way...
http://www.thesamba.com/vw/archives/manuals/techbulletins/z14.phpAlso, not sure if the points in a US '66 would be the same as early, otherwise I would take some pics for you.
There has been many discussions on the subject on that
other site linked above. You might try a search there.