I have a 1994 K series blazer with 4WD. I recently began hearing a knocking noise from under the vehicle. It first sounded like the front drive shaft, but I began having the 4WD "stick" slip into neutral. Could this be caused from the drive shaft?? I have been told there is a clip that hold the shifter in place until it is moved is this correct? Or is my transfer case about shot...

*Combining Double Post which had a better description*

I have a 94 full size blazer. I have been experiencing a tinging noise under the truck, can feel it in the floor, also a times the 4 WD shifter slips into neutral, I have to shift it back into 2wh to keep moving. I checked the fluid in the transfer case and its full of ATF. I have been told there is a pin that holds the shifter in place until manually moved. Can someone help please.....

 

Since you have the the shift lever on the floor, you have the NP241 transfer case.

Is the ticking in time with ground speed (increase in frequency as ground speed increases)?

The slip into neutral in the transfer case could just be a shift lever out of adjustment or bent.

 

The thumping sound occurs at all speeds. I've been cautious about hitting
bumps until I find out what it could be. At times when i coast over speed
bumps it even makes a light noise. But at times I can drive without a noise
at all.The other day I tried to put it into 4H but it seemed bound up. I was
able to take it into neutral then 4WL. I checked the shifter arm under the
truck and it seemed ok. Now there is a bit of play in the shifter inside the
truck.I did turn the front drive shaft and could hear a small thumping sound
inside the transfer case.( the engine was off). Thanks for your help.

 

If you hear the thumping noise while just turning the front driveshaft with the engine off, then it is likely something inside the transfer case.