"I have a 97 2500 Ram, when the truck is in 2 wheel drive and I drive 10mph there is a grinding noise under my seat, but i can feel it in the brake pedal. It also grinds in reverse at 10mph. If you drive past 13mph the grinding fades away. My dad and I spent the last three day's replacing all the front end, including the wheel hub'$$$ thinking that the right hub was making the noise b/c it was bad, but $600 later and still the noise. Could this noise be that ring your talking about?"

 

Okay,
This morning I took it out to Muffler man so they could get it up in the air to see if we could simulate the noise and look under the truck at the same time. We did indeed simulate the noise by placing the truck in 4wd hi and goosing it a couple of times, then at 12 mph the grinding started up. When the tech was in the truck giving it gas I walked to the back of the truck and listen, I thought what the heck, and sure enough I could hear it at the rear. When it was grinding the drive shaft to me looked as if was bouncing when it was making the grinding noise. It's not the ujoints b/c my dad and I just replaced them two day's ago, and when I'm driving I can drive past 50mph without getting a back massage. The tech thinks the truck is stuck between 4wd and 2wd, and my dad thinks it's in the chain.

 

Do a search for "tranfer case snap ring" and "transfer case saver." It sounds like the snap ring broke. I plan on replacing mine with a t-case saver in the near future to avoid that problem. From what I've read it's easy to replace, just take off the driveshaft, remove the tailshaft cover, then pull off the old ring and screw on the xfer case saver.