Chevrolet: 1995 gmc van, critical measurements, gmc van

Question
I have a 1995 gmc 2500 series vandura with 138,000 miles.There has been intermittent chattering noise coming from differential lately.I removed diff. cover and drained fluid and found minimal particles but noticed when i rotated wheels a little the square box with gears inside had some play in it.Inside of box was a round sleeve that each end was visible and when i moved wheel back and forth there was obvious play in the pin.I noticed there was an 8mm bolt that retained pin in location. Visual exam of all gears looks fine.Could loose sleeve be point of concern and how do I  fix?    thanx,jerry  

Answer
If the play is in the pin that the 8mm bolt holds in, then you will have to replace the differential. Its the part that has the small gears inside and the large ring gear is bolted to it. If you have never rebuilt a rear end before you should take it to the dealer. There are a lot of critical measurements and adjustments that need to be made or you will have more problems than when you started.