Rear end noise

[hotdawg23]

It was indeed a hotshot truck as evidenced by the gooseneck ball in the bed, trailer light hookup etc. Guess the guy was on the road all the time. There is a little slack in the pinion area when the shaft is rotated back and forth but not much. There is no clunk when dropping in gear or reverse or shifting. It does have the factory engine brake which may have caused the wear on the rear end but why no noise when running steady and noise stops at about 25MPH. I said earlier it was 10 MPH but i retested it just now and it is more like 25.
I haven't pulled plug on rear end yet but is my next task.
Thanks to you all and i feel we will narrow this down to the real problem very soon.

[chevyguy]

Man I would get the oil out now and get the right stuff in there. I am betting it deosnt have the posi additive. You rear differential should be a dana 70 since you have the V10.

[gmctrucks]

Originally Posted by hotdawg23

Thanks for reply. I just bought the truck and it does look like the oil had been changed recently as there was oil around the filler plug. What kind of additive should i use? ooor is it too late for that?

From what I heard GM has a good one to put in it. I'm buying my additive there when I have my Auburn posi put on I have been saying that forever but things always come up and im the only one that pays bills here. But every so often I take it out of the box and look at it.
GMC