I have a 1998 ram, swb, rc, 4 X 4, 360, auto. I've had it since new. It has 153k miles. Since about 90k miles or so, it's made a vibrating/growling noise under load at low rpm's. It generally does it when the truck shifts into OD, but will do it with the OD button off if you can keep the rpm's low while accelerating under load. At first, you could only hear it with the back glass open. It has gotten louder over time and you can now hear it with the glass closed. It makes the noise most noticeably when cruising through town or 2 lane hwy at 45-50 mph. Once past 60 mph, it is almost totally gone. Now I do not believe it is indicating immenent failure, since I've been told the following:

First mechanic says "I can't hear it, I've worked near the train tracks for years and can't hear well."

Second mechanic says, "I hear it...but I don't know what it is. I doubt it's a problem."

Driveline specialist says, "I hear it...I don't believe it's in the rear end. It does not sound like gear or bearing noise. I think it may be the torque converter. Take it to transmission specialist X."

Transmission specialist X says, "It's not the torque converter. I don't know.."

Last mechanic, "Next time you're in for an oil change, we'll put it up on the rack. I wouldn't be afraid to drive it to California (which is a long way from here)."

So, basically, I might let the guy change the oil just so I can use his rack. Unfortunately, the vehicle will not be under load, so it probably won't make the sound anyway. I've crawled around under the truck looking for loose heat shields, etc, but I can't nail it down. I posted on this before...I believe Purpl Dodge had the same noise, but he didn't know what it was either. I have two TSB's that are a possibility...but I don't want to replace the driveshaft or rear gears just to alleviate a noise that according to the mechanics, may or may not be driveline related. TSB's are TSB 16-01-95 and TSB 18-49-98 for those interested.

I'm hoping someone else out there has had this noise and can point me in the right direction. If not, I guess I'll live with it like I have for the last 60k miles. The noise isn't huge...but it annoys me.

Thanks.

 

Check the transfer case, and see if the snap ring for the rear output shaft has broken. Drop the driveshaft, grab the output shaft, see if it moves...... (in any direction.)

 

While you have the drive shaft out, check the ujoints.

 

Well, I guess I will drop the driveshaft. Will prolly go ahead and change the u-joints, since they are the originals. It sounds nothing like what I've heard in the past with bad u-joints. And I kinda think it would be much worse by now after hearing it for 60k if it was u-joints. But...can't hurt anything but the wallet a lil.