Hi all - recently purchased a clean '96, but there is a rapid clicking/buzzing sound happening when I shift in 2WD. When shifting into 4-lo or 4-hi, sound goes away - almost like the 4wd is not fully disengaging going back to 2WD. I have 3 buttons on the dash to shift. The noise speeds up and down as the vehicle speed varies, I can hear it most slowing down past 40 / 30/ 25MPH. It best is described like the noise a playing card in a bicycle tire would make....

Since this I just bought the truck, giving it the "once over" I did find an unattached vaccuum line on the top of the trasmission (this "T" is plugged into the trans and has 3 small lines running to it. (Located driver side area on trans), I did hook this vaccuum line back up to the transmission and now notice this noise occuring....?

Any ideas, or can someone tell me where I can locate a vaccuum line diagram for this year? 1996 V-6. Thank you!!

 

There's a thread for that:
4wd Front Axle Clicking When in 2HI - Goes Away when in 4HI/4LO

 

Thank you! I have found a few threads that will help me with some other issues as well. Thanks for the help and the forum!