The coupe has developed a new rattle/banging in the backend that has
increased over the trip.
It kinda feels like something bumping the floorboard, so my first
thought was the exhaust, I slid under and shook the pipe,
but could not replicate the sound. Shook the wheels and CV's
nothing, but I did notice a very wet/oily shock on the pass.
side......could this be the source?

I did not have the car jacked up, so I couldn't get into the shock
to try to shake it.

__________________
81 Mercedes 300SD 289k.......SOLD
82 Mercedes 300CD 252k......slow ride

82 mercedes 300 SD...mi Unknown
83 Mercedes 300D ????ksniff..gone too
84 Mercedes 300D 148k........SOLD
85 Mercedes 300TD 386k and holding some one elses project

There are a lot of things that could cause a rattle, too many to get into here with the information given. Could be as simple as something loose or could be worse than that. Go to somebody you trust to give an opinion of the cause and then maybe go and get a second opinion.

Arnold, you are carpet-bombing posts here lately at a staggering rate!! Your accuracy doesn't seem to be keeping up with your bulk.
I think Jack is qualified enough to check for obvious signs of something loose without needing to go to two different mechanics. Besides, if you're following along at home, he is out on the road. When out on the road, there is no mechanic you trust!
Besides, the info he gave provides enough evidence to warrant giving that shock a closer look when he is able.

__________________
Jimmy L.
'05 Acura TL 6MT
2001 ML430 My Spare

Gone:
'95 E300 188K "Batmobile" Texas Unfriendly Black
'85 300TD 235K "The Wagon" Texas Friendly White
'80 240D 154K "China" Scar engine installed
'81 300TD 240K "Smash"
'80 240D 230K "The Squash"
'81 240D 293K"Scar" Rear ended harder than Elton John

Could be, but usually a leaking shock just doesn't act and react as it should, vs rattling. Are you able to check the sway bar links?
Good luck.

__________________
83 SD

84 CD

Not today, it is raining here. I will say that the sound seems to
be coming from the Drivers side, while the "wet shock" is on the
pass. side. I am also noticing that the backend seems to list to
the pass side.

I am mostly hearing it on slightly bumpy terrain, and keep in mind,
this thing is loaded.....not over loaded I don't think, but a good
load all the same.

I am also not noticing anything out of the ordinary as far as
handling.....just the rattling.

I will most likely just go with it until I get to San Antonio then
get it unloaded and up on stands.

I once had an old ford torino that had a control arm up front
go bad, It would shimmy and shake something fierce,.......and
rattle the front end. That is the sound as best as I can describe it,
but no shimmy and shaking.

Drive shaft flex disc maybe?

__________________
81 Mercedes 300SD 289k.......SOLD
82 Mercedes 300CD 252k......slow ride

82 mercedes 300 SD...mi Unknown
83 Mercedes 300D ????ksniff..gone too
84 Mercedes 300D 148k........SOLD
85 Mercedes 300TD 386k and holding some one elses project

When I found the UCA bushing was bad on my '82 300D, I had uneven tire wear, and, I felt excessive body roll, that's all.
You may be noticing the sounds from the drivers side due to your orientation in the car.
I would think the center bushing/bearing would provide you with a "stuttering" in the drive train, especially during steady speed, but I'm hardly an expert. Should be able to feel it in the seat too.

Good luck with your trip.

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83 SD

84 CD