I found a few threads from searching about my problem, but nothing that quite diagnoses the problem the way I see it. Let me see if I can make any sense of this.

It's a 2000 Ram 1500, 5.2L Auto Tranny, 147k miles with a CAI and the muffler hacked.
I feel a vibration that almost feels like it is in the transmission/t case, or from the driveshaft. I feel it at any speed, in any gear but only under certain conditions.
Whenever I barely have the throttle cracked, just enough to kindof coast/accelerate slowly, it will grind and vibrate faintly as if the friction plates are shot. The vibrations don't really come from the suspension, or from the tires/brakes. I feel it all around. Like I said, it will do it at any speed in any gear as long as I am feathering the throttle very very lightly. It's most noticeable at freeway speeds or anything after 40 when i get the TC to lock up. When i let off the throttle all the way it will grind and vibrate for just a second, then it goes away as I coast and slow down. I don't feel it when I'm on the gas accelerating either.
One other thing I noticed today while doing some freeway driving, is that when I am braking I can hear some sort of a clicking, as if the u-joints on the driveshaft are going out, but I don't feel that same vibration and it sounds like it's legitimately coming from the driveshaft. I don't feel anything in the brakes when this happens.
I also noticed today, I was on a slight incline, (a little more than a driveway) and put it in reverse to back up quite a ways and as I let it coast I could really hear the same clicking I heard when slowing down from freeway speeds. I'm not sure if all three situations are related or not. I have not yet had the chance to check the u-joints on my driveshaft, I will be checking tomorrow, I just can't sleep thinking about it right now. If you guys have any ideas, or know of any previous threads that I couldn't find, shed some light

 

stop driving it until you check your drive shaft ujoints. if they come apart while driving you'll break some expensive parts.

park on level ground, block wheels, trans in neutral, e-brake off, all tension off the drive shaft.... grab both ends of the u-joint and twist back and forth. any movement indicates bad. missing seal indicates bad. if you can get a grip on it, stick a screwdriver through the cross and try to pry it apart. should be no movement.

 

I second that, When my front u joints went bad I was getting a grinding metallic sound that I would have sworn was coming from the T-case. I've heard U-joints cause all sorts of noises and vibrations when they go. You have to remember how fast they're spinning, articulating and the stresses they're under. At this point you may not even have slop yet it may just be to the seizing point. After that stage, the slop begins and that's when it becomes very dangerous.

Remember, a noisy U joint should be replaced. After it's gone quiet, you're on borrowed time!

 

Is this in a 4x4? Not sure if the second gens still use it, but, as found on my first gen, a bad centering ball (double cardan joint) in the front driveshaft can give those same symptoms. I agree with the above: Get all forces off of the driveshafts, and give them a wiggle. Also, give a good shake to the pinion on your rear axle. Sometimes the pinion nut will back off, or the crush collar will cave in too much, putting your backlash out of spec. and give the same symptoms of a bad u-joint.

 

Yeah same thing. My centering ball took a sh*t on mine too. Twice. The second time it sheared the "pin" in the center right off so I ended up with a new shaft. Since his is a 2000 AND a 1500 they still had the CAD unit so in 2wd (if it's a 4x4) the front shaft shouldn't be spinning assuming the front drive system is working correctly.

 

Yeah I got home from work today, crawled under there and checked out the whole thing from front to back, last thing to check was the rear u-joint, sure enough that sucker was loose as ever. I'm surprised it didn't break sooner, I was already on borrowed time! Luckily Autozone was still open so I was able to slap a new one on there in no time and grease up the others. Now it's riding smooth as ever!!

 

Good to hear!!