2001 Dodge 2500 4x4 vibration 60 to 70 mph

it could be center bearing, if its going bad it can also cause a vibration, make sure you have sufficient fluid in the diff as well, you can also get a noise and vibration from collapsed motor or trans mounts

could be a u-joint

Check the rear end or if it's a 4x4 check both axles, if the pinion losened on you it can cause this.

what about it?

conventional axle or limited slip? Get axle code off door sticker.

SECTION 205-02: Rear Drive Axle/Differential - Ford 8.8-Inch Ring Gear 1998 Explorer/Mountaineer Workshop Manual
IN-VEHICLE REPAIR Rear Wheel Bearing and Axle Shaft Oil Seal -4.0L SOHC and 4.0L EI, Conventional
Special Tool(s) Axle Seal Replacer
T83T-1175-A Axle Wheel Bearing Puller
T83T-1225-A Axle Wheel Bearing Replacer
T83T-1225-B Driver Handle
T80T-4000-W Impact Slide Hammer
T50T-100-A
Removal

1. Remove the axle shaft; refer to Axle Shaft in this section.

Axle Shaft Removal

1. CAUTION: Do not use heat to loosen a seized lug nut. Heat can damage the wheel (1007) and the rear wheel bearings (1225).
   Loosen the lug nuts (1012).
   1. Remove the center cap.
   1. With the weight of the vehicle on the wheels, loosen the lug nuts.

1. Raise and support the vehicle.

1. Remove the wheel and tire assembly.
   1. Remove the lug nuts.
   1. Remove the wheel and tire assembly.

1. Remove the axle housing cover (4033).
   1. Loosen the axle housing cover bolts (4346) and drain the rear axle (4001).
   1. Remove the axle housing cover bolts.
   1. Remove the axle housing cover.

1. Remove the rear disc brake rotors (2C026); refer to Section 206-04 .

1. CAUTION: Once the differential pinion shaft (4211) has been removed, turning the differential case (4204) or an axle shaft (4234) will cause the differential pinion gears (4215) to fall out of the assembly. This could result in chipped or damaged components.
   Remove the differential pinion shaft.
   1. Remove the differential pinion shaft lock bolt.
   1. Remove the differential pinion shaft.

1. CAUTION: Do not damage the rubber O-rings in the U-washer grooves.
   Remove the U-washers (4N237).
   1. Push the axle shafts inboard.
   1. Remove the U-washers.

1. Reinstall the differential pinion shaft.
   1. Install the differential pinion shaft.
   1. Install the differential pinion shaft lock bolt finger-tight.

1. CAUTION: Do not damage the inner wheel bearing oil seal (1177).
   Remove the two axle shafts.

Installation

1. Lubricate the lip of the inner wheel bearing oil seal.
   • Use Premium Long-Life Grease XG-1-C or equivalent meeting Ford specification ESA-M1C75-B.

1. CAUTION: Once the differential pinion shaft has been removed, turning the differential case or an axle shaft will cause the differential pinion gears to fall out of the assembly. This could result in chipped or damaged components.
   Remove the differential pinion shaft.
   1. Remove the differential pinion shaft lock bolt.
   1. Remove the differential pinion shaft.

1. CAUTION: Do not damage the inner wheel bearing oil seal.
   Install the two axle shafts.

1. CAUTION: Do not damage the rubber O-rings in the U-washer grooves.
   Install the U-washers.
   1. Position the two U-washers on the button end of the axle shafts.
   1. Pull the axle shafts outward.

1. Install the differential pinion shaft.
   1. Align the hole in the differential pinion shaft with the differential pinion shaft lock bolt hole.
   1. Install the differential pinion shaft lock bolt.

1. Install the rear disc brake rotors; refer to Section 206-04 .

1. Install the axle housing cover and fill the rear axle housing (4010) with 2.4 liters (5.5 pints) of specified lubricant; refer to Axle Housing Cover in this section.

1. WARNING: Always remove any corrosion, dirt or foreign material that may be present on the mounting surfaces of the wheel or the surface of the wheel hub or rear disc brake rotor that contacts the wheel. Installing wheels without proper metal-to-metal contact at the wheel mounting surfaces can cause the lug nut to loosen and the wheel to come off while the vehicle is in motion, causing loss of control.
   Clean the wheel hub and mounting surfaces.

1. Install the tire and wheel assembly.
   1. Position the tire and wheel assembly.
   1. Install the lug nuts and lower the vehicle.
   1. Tighten the lug nuts.
   1. Install the center cap.

1. CAUTION: Never remove the axle shaft oil seal by itself. Always remove the rear wheel bearing and the axle shaft oil seal at the same time.
   NOTE: If the axle shaft oil seal is leaking, the axle housing vent may be plugged with debris.
   Use Impact Slide Hammer and Axle Wheel Bearing Puller to remove the rear wheel bearing and the axle shaft oil seal.

Installation

1. Lubricate the new rear wheel bearing.
   1. Use Thermally Stable Rear Axle Lubricant XY-80W90-QL or equivalent meeting Ford specification WSP-M2C197-A.

1. Use Axle Wheel Bearing Replacer with Driver Handle to install the rear wheel bearing.

1. Lubricate the lip of the new axle shaft oil seal.
   • Use Premium Long-Life Grease XG-1-C or equivalent meeting Ford specification ESA-M1C75-B.

1. Use Axle Seal Replacer with Driver Handle to install the axle shaft oil seal.

1. Install the axle shaft; refer to Axle Shaft in this section.

SOUND LIKE WORN DRIVE SHAFT BEARINGS AND A LEAKING DIFFERENTIAL PINION FLANGE SEAL.

Top of Form 1
Raise the vehicle and remove the rear wheels.
Clean all dirt from the housing cover and remove the housing cover to drain the lubricant.
Remove the brake drum.
Rotate the differential case until the differential pinion shaft lockscrew can be removed. Remove the lockscrew and pinion shaft.
Push the axle shafts toward the center of the vehicle and remove the C-locks from the grooves on the axle shafts.
Pull the axle shafts from the housing, being careful not to damage the bearing which remains in the housing.
Inspect the axle shaft bearings and replace any doubtful parts. Whenever the axle shaft is replaced, the bearings should also be replaced.
Remove the axle shaft seal from the bore in the housing, using the button end of the axle shaft.
Remove the axle shaft bearing from the housing. Do not reuse the bearing or the seal.
Check the bearing shoulder in the axle housing for imperfections. These should be corrected with a file or polish.

i would suspect bad driveshaft hanger bearing - to confirm, jack up back end of truck and hold up with jack stands. have someone in the truck to accelerate to the speed where you hear the noise, listen for the noise - a stethescope is very useful for this. good luck!

possibly bearings. but i wouldnt drive it till you check it out cause if its just the bearings you could possibly save the ring and pinion. it could be the ring and pinion and if it is you will need to either replace or rebuild the rear end.

PINION BEARING ALSO CHECK FOR CHIPS IN THE PINION GEAR IF LET GO IT WILL TEAR UP THE REAR END IN WHAT EVER VEHICLE YOUR DRIVING

Your carrier bearings and possibly the pinion bearings are the source if the noise is a low pitched grumble or gravelly noise that starts just about 20 mph and up. If it is louder when quickly changing lanes to the left, it is probably the right wheel bearing, and if it is louder when changing lanes to the right, it is the left wheel bearing. If it is a whine that is really annoying at 45-65 mph, your ring and pinion are probably worn beyond their design specification limit. If your U-joints are OK, but you can hear a loud clunk from the rear when you get on and off the throttle, you definitely have play in your ring and pinion. Have the cover removed and you can sheck this easily. I have worked on several Jeep Grand Cherokee differentials, and the ring an pinion has needed replacing on them all. A few had bad bearings, too. You should probably replace the bearings and the ring and pinion, because the labor is nearly the same and the parts are just a bit more. If you look through the forums on the www you will find many people that replaced the bearings to fix the grumble, only to finish the job and find out they also have the whine.