I have a 2000 Blazer LT 4.6 4wd and recently have been hearing a noise like a rattling at speeds from 30-50mph. It is not consistant with the speed more variable and not when I hit bumps or rough roads.Trying to locate this has been frustrating. One thing I had noticed today is the front drive shaft moves slightly (less than 1/8 in.) both laterly and horizontly and makes a noise. My question is this movement normal or is this the cause of my noise problem. How difficult is it to replace and does anyone have a source to get a replacement. Thanks in advance for any help.. Dave

 

Are you talking about the drive shaft that comes from the transfer case to the front end or are you talking about the cv axle shaft that goes from the front end to the wheel ?

 

It's the drive shaft going from the transfer case to the front end. The vehicle has 153k miles on it and I only use the 4wd a handful of time in the winter just wondering how it could go bad

 

The U-joints may be bad, they aren't expensive and not too terribly difficult to replace.