Just bought a 1998 Quad cab short bed 4x4 5.9 auto 3.55 anti spin 76,500 miles. It sounds like rear end noise is it normal for these or am I going to need to replace all the bearings. I put in mobil 1 75w90 synthetic and repalced the rear U Joint still there.

I was told with short beds the rear end was closer to the cab so it was a little noisy.
I have a 1990 D350 cummins no noise there but this is the first 94-01 series I have owned.

 

is it making an howling noise

 

You've got the exact same build as I do ... I've had rear axle noise for 10s of thousands of miles. Sounds a bit like a brake drum dragging (it isn't). I noticed some wobble on the yoke that attaches onto the pinion shaft. I think mines got a slight warp in it (the pinion shaft). The noise varies as to whether I'm accelerating, decelerating or floating it (silent then).

 

TMS you got it.
Mine is an SLT Laramie and the noise is exactly as you described. I removed the the rear seat and carpet and installed dynamat sound insulation from the rear of the front seats all the way up the back wall to the bottom of the window. Taking a trip to Connecticut tomorrow will see if it makes a difference.

 

That may help when the windows are up ... I can hear mine echoing off of whatever I'm driving beside ... even a curb.

 

Got the same problem------- 98 quad cab 360 - 3:55 axle - 168000 kms.

 

Took a trip this weekend it is quieter at speed. At slow speed and comming to a stop makes more noise almost like a wind down click click click untill you stop but on the highway seems to be fine to performance problems. I am just curious if the pinion bearing may be bad.

 

i had the same noise and even though the synthetic oil says for limited slip i added an limited slip additive and the noise was gone. worked perfectly. hope this helps

 

The posi additive will only really help when turning a corner. Unfortunately, the only real way of fixing it is to take the rear apart. My 99 was making alittle noise and i had to put a new carrier in because the side bearing wore into the carrier causing the backlash to be out of spec. I also see that you have a GM rear brake conversion on your truck....maybe it has to do with something that was done at that time.

 

I added the 1-ton wheel cylinders last summer. I've had this noise for about 6 years now. Pretty sure it's the pinion bearing. If it grenades ... it grenades. I'm looking for an excuse to swap in a pair of D60's anyway.