Originally Posted by moosehauler05'blaz

There is a gear in the transfer case With a selector arm In 2WD nothing is used Once you push the 4WD button That arm sets the gear into the other giving you 4WD If you have a bad vaccum leak / encoder You will have the arm only go in half way Chewing your carrier gear (Differential Carrier Gear Kit Front Dorman 600-561) There is no need to buy a whole diff unless its under $100 And you feel like paying extra on labor Myself i replaced the gear And the actulator under the battery Along with the vacuum actuator switch And checked all my Vacuum lines There is Youtube videos for how to remove and install your carrier kit which is simply removing washers in order The gear Then putting the new ones in. in the same order ..If your feeling mighty...buy a new cable too and clean the mounting area

Originally Posted by Micah Ransler

Let me start by saying that I searched this site for 3 hours and I didn't find my exact problem. So I'm creating a new thread.

I have a 4x4 1999 S10 Blazer. Not sure if this matters, but it's a LS.

There is this really awful rattle coming from somewhere underneath the car. Took it to the shop, and my mechanic said that it was coming from the t-case, and that it needed to be replaced (as well as the encoder motor).
So I replaced them both with used parts from my other blazer, but the noise remains. Also installed new universal joints and front and back driveshafts.
I don't know what this noise could possibly be because I know the replacement t-case and encoder motor are good. Any help would be much appreciated.