Answered my own question.

I forgot that I had a CD-version of the factory manual (once you have a paper manual its very easy to forget) and it's covered there.

Yes, those are the marks (two parallel lines on the ujoint yoke and one at the hex on the front tube. So, I guess that means I can put my 84 shaft together using those marks.

If I interpret what they are saying correctly the manual also states that the mark was present before August 82 but they didn't bother to use them to balance the shafts (?) So, I guess that means that if you have a pre- August 82 shaft, you see the marks, you separate it, you align the marks, you shafted yourself!

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80 300SD (129k mi) 82 240D stick (193k mi)77 240D auto - stick to be (153k mi) 85 380SL (145k mi) 89 BMW 535i 82 Diesel Rabbit Pickup (374k mi) 91 Jetta IDI Diesel (155k mi) 81 VW Rabbit Convertible Diesel 70 Triumph Spitfire Mk III (63kmi)66 Triumph TR4a IRS (90k mi)67 Ford F-100 (??)