Ok I have had this issue for awhile now, I just havent been able to pin point a solution without just dumping parts at it. , ive discovered that there is a loud clanking noise when shifting to reverse whether it being from park or from drive. I also been feeling vibration when letting off the gas and coasting at highways speeds. I can also hear a clank or kick when gettijg back on the gas. Now today I was driving down the interstate. Was forced to push my truck lot harder than i should have and. The vibration got real bad and inoticed lots of gray smoke in my rear view. I pulled of a exit and noticed a fluid dripping from the front side of my rear end any ideas or incite of what my problem(s) might be?
ps. I wanted to attach a video, but it wouldn't let me upload a mp4 format.

 

Upload the video to youtube, or someplace similar, then link to it here.

What year is your truck? Engine? Trans? 2 or 4 wheel drive? How do the u-joints look? Also, think I would be having a look at pinion bearings, and fluid level in the rear diff.

 

Yep, u-joints, pinion bearing, differential.
Bad pinion bearing will usually sling oil all over the underside of the truck just forward of the rear diff. There are videos for checking pinion play.
I'd want to get a look at rear gearing. Remove the cover and check for unusual wear. See if you get metal chunks in oil or at the bottom of the diff near the magnet.
Also see videos for checking u-joint play.
It's the black smoke that concerns me, unless you have a cummins. I wouldn't drive it until you know the problem.

 

Here's the video that I wanted post originally. I haven't had much time to do anything with however I did crawl under and got a closer look at the U joint.. I'd say it is definitely bad, I found piece of rubber that seals the caps sticking out. I check the fluid level of the rear diff, and I couldn't feel any at first. So I refilled it and it only took a half quart. So hopefully tomorrow I can get to inspection of inside of the inside of the rear differential.

 

Good work on finding bad u joints. You might as well replace both sets of u joints (both ends of the drive shaft).
Be sure to mark the drive shaft mounts so you re-install correctly.
The play in the video looks like excessive backlash. The way to tell is to check for play by turning the yoke nut when you have the drive shaft off. Let us know if you are getting play and we can go from there.
Hopefully your differential fluid is clean.

 

Thanks, good point. I will change both U joints. I was just getting ready to crawl underneath and check the fluid level again. The fluid I did get on my finger before I topped it off with the half of quart, was really black and smelled horrible. But then again even the new stuff smelled the same way. So hard to judge on that. I want to inspect the inside and change the fluid anyways. So when I am at O'Reilly I will pick up 2 u joints, a diff gasket and some 75w-140. I just want to make sure I have all my ducks in a row before I go, because once I start I won't be able to go back with my truck taken apart.

 

New U joints are pressed into driveshaft. Before I put the driveshaft back in, I need to address this mysterious piece of metal I found in the rear differential when I pulled the cover. Any ideas?

 

Still cant see where that piece as pictured above came from. There isn't any side to side play in the pinion shaft from the front side of the rear diff. Here a video of play in the pinion gear itself. Sorry for it being so shaky. Haha

 

That is the c clip that holds the clutch packs together. If memory is right there are 4 of them. two on each side. You may wish to search those here. Common failure

 

cool thanks, I did just that. Here the thread I found.
https://dodgeforum.com/forum/2nd-gen...ferential.html
Now my question is, this is clutch clip something that belongs in the carrier? Who knows how long that clip has been broken, I have already put it all back together, so I don't think I am going to worry about it. .