Hi all- 1984 300D turbo
so from the little info there is on the aforementioned topic, what is the role of the flex/giubo joints? Are these parts located in the transfer case- where the main driveshaft inserts, or externally? How much play should there be between the axle drive shafts and the transfer case and the main driveshaft? How much play (up/down) should there be in the main driveshaft?

Is a combo of these issuse what is causing the "clunking" from the rear end or is it the driveshaft bushing and bearing assembly?

Further detail: there is some clunkiness during acceleration, which i attribute to an unknown vacume leak, but would that vacume leak cause excessive clunking, bordering a slam, from the rear end on hard(er) breaking or is that the flex/guibo joint(s)?

The car goes into the shop (for the first time I have owned it) on Monday and I want to be prepared, if not preempting. If there is a problem I can diagnose and repair before she goes in, I will do it.

As always, any help is appreciated.
Ben