It looks pretty straight forward and I did look at some threads here. This is what I came away with mainly common sense items.
1. Mark both halves of the driveshaft where they come together.
2. The manufacturers markings on the rubber portion should face forward ?

I am also replacing the center support bearing. Thoughts ?
Thanks
Alan

__________________
92 500E Silver 66k
82 Porsche 911SC 84K
68 Cadillac ( Gone Now )
03 Suburban Z71 200K
85 300SD 217k From Original Owner ( Dad )

Bad flex disk driving home
Bad flex disk driving home - PeachParts Mercedes ShopForum

Bad Flex Disc
Bad Flex Disc - PeachParts Mercedes ShopForum

Weekend Wrenching (a great picture of a bad flex disc)
Weekend Wrenching - PeachParts Mercedes ShopForum

The Death of a Flex Disc ... did I kill my 240D?
The Death of a Flex Disc ... did I kill my 240D? - PeachParts Mercedes ShopForum

What happens when you ignore that "little" driveline vibration!
What happens when you ignore that "little" driveline vibration! - PeachParts Mercedes ShopForum

Flex Disc Orientation, safety and durability issue.
Flex Disc Orientation, safety and durability issue. - PeachParts Mercedes ShopForum

If your W123 is shaking down the highway. . .
If your W123 is shaking down the highway. . . - PeachParts Mercedes ShopForum

Correct way to install front driveshaft guibo? (FLEX DISC)
Correct way to install front driveshaft guibo? - PeachParts Mercedes ShopForum

Do you have the right puller to withdraw the center bearing?
If you drop the diff a few inches the drive shaft will slide past the alignment center without using a pry bar. Place a floor jack under the diff, undo the four bolts going into the cross frame, real easy. Lower six inches. First remove the tunnel pan.
Enjoy the job.

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1984 300SD turbo 126
"My true love"

God made me an atheist and who am I to question His wisdom

W126_Rubber Boot_drive shaft center support bearing
W126_Rubber Boot_drive shaft center support bearing - PeachParts Mercedes ShopForum

W126 drive shaft carrier/center bearing DIY
W126 drive shaft carrier/center bearing DIY - PeachParts Mercedes ShopForum

Thanks , As always excellent information. I will get started Sunday a.m. but then need to take the kids to Moms around noon. Plus I need to trouble shoot an issue I posted in another thread about power loss. I believe it is a throttle linkage issue.
Thanks
Alan

__________________
92 500E Silver 66k
82 Porsche 911SC 84K
68 Cadillac ( Gone Now )
03 Suburban Z71 200K
85 300SD 217k From Original Owner ( Dad )