Actually the Manual has that after Aug 1982 they used those makes to line up the Drive Shaft Sections. See the pic.
Before that date the marks are there but the Factory did not pay attention to lining them up.
That means if His Drive Shaft is original to the 1985 CD the marks should have been used when the Drive Shaft was assembled.
That means if the OP lines up the Marks on the Drive Shaft and is still having vibration the vibration could be cause by some other problem.
Sticking U-joint causes Vibration that Rips up several Drive Shaft Supports turns out to be Rusty Needle Bearings
http://www.peachparts.com/shopforum/diesel-discussion/338641-w123-propeller-shaft-vibration-tears-up-rubber-mounts-replaced-nearly-everything-3.html
In any event anytime you take apart something that can go back to gether in a different position it is always a good idea to make the position it is in, take some pictures or make a drawing (and don't loose it).
If you don't you find youself eventually geting diverted from some job you are on and not being able to come back to it in time enough for your memory to be entirely sure of things.
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