It's a 97 4dr. blaze,4x4, 4.3 like all of um. My rear diff and axel makes a very loud distinct 'clunk' when put in gear, and just today started making that same noise when hitting any bump even as small as a penny almost. I can push the rear end side to side and it sounds as if the rim isn't tightened, but it is. And it does it on both sides. I'm thinking the axel/diff is diffenently loose and some parts will need replacing...What exactly would it be though? Please help! It's driving me nuts! lol. Thanks!

 

Did you check the u-joint first to see if it has any play in it? A lot of times the clunk you hear when it is put in gear is the u-joint.

 

I second that. A freind of mine had this issue, and it was the u-joints. So he replaced those, now no-mo' clunking.

 

i challenge that. I say wear in the rear end bearings, all of them. But its worth it just to check the u joint first instead of assuming a pinion bearing right away.

My rear end has the same symptoms to a T. No leaks so I put synthetic gear oil in it and am going to ride it out until i upgrade to a disc brakes rear end. You should be fine for a while, but bearings are dirt cheap.

worn shaft bearings causing too much side to side play until the axle c-clip catches & worn pinion bearing causing too much play in the pinion & ring gears, clunk.

 

how do you check the u joints? i got this same roblem going on. i put in a whole new used rear diff. less than a year ago and a new tranny about a year ago so im thinking its a u joint problem. I just dont know how to check to see if there going bad

 

with truck off put the emergency break on, and the transmission in neutral. crawl underneath and grab the drive shaft. twist it back and forth and see if there is any play in the u joint. it should be tight, no play.

 

That works real good but most of the time you usually don't even have to twist much. You can see if it's shot when it makes a bunch of noise. If it's real bad they really go downhill pretty quick.