hello i have a 97 blazer and i took it muddin the other day and today i relized that there is Clicking in rear end i put it in nutral and coast and no clicking it just does this in drive.. Im going to see later on today or tomorrow if there is anything like mud that could be making this noise.. any Suggestions as to what this may be. thanks

 

Could be a u-joint. They can sometimes make a noise when loaded and quiet down when coasting.