Possible bad transfer case?
 

well im back at unfortunately. Recently while driving the ole blaze I heard a loud click, click, click noise coming from the truck while going down the road, and nothing at idle. I originally thought well could be a bad drivers wheel bearing seeing how I already changed passenger side. well I inspected the wheel bearing and all is good there, but then noticed that it seems to be coming from under neath the truck, I checked into it and you can hear a faint clicking noise while manually spinning the front drive shaft and what seems to be coming from the transfer case. What in the heck could have gone wrong inside that thing? My second question is I know apparently have an annoying vibration coming from inside the dash on the drivers side all of a sudden. Any thing that is common in there I should check? I appreciate all the help!

Are you sure the noise is coming from the transfer case and not from the front axle? There is a disconnect inside the front axle that can click if the cable isn't releasing properly.

transfer case whinning
 

My transfer case was making a whining noise, I found a broke vaccum line on top of the transfer case...replaced line, no noise for the past 3 months

I have a 98 Blazer 4x4 with a three button selector, when i put it in 4H or 4L i hear the transfer case go into gear, also my front axle is engauging ok, when i try to accelerat i get a very loud clunking, almost like it is trying to come out of gear, could it be the shift motor,cv joints are ok as is the drive shafts, thanks for any help. Sulley

How have you determined that the front axle is engaging properly? Does this clunking only occur while turning or while going straight as well?

I have manualy engaged the front axle by taking off the vacum accuator and used a pair of visgrips .yes it does it going straight but only when i am accelerating, if i am just cruising it will not do it.Turning it also does it any time and any direction. Sulley

Sry I haven't replied recently as I am currently in the process of painting the truck. Yes, im 100% sure it's coming from the transfer case. Not too sure if it's low on fluid or what. Will have to look into it soon tho.