im not too sure if this is where i should post this but .... i have a strange howling coming from the rear end it only happends as i am driving and i release the gas and then the howling starts but as soon as i give it some gas it stops.... any ideas??? i had a friend of mine tell me that GM has a rear end fluid that is made for this reason... is this true? any help would be great thanks

 

That was the first symptom that mine was going bad. I think it's 'cause the teeth are wearing, increasing the clearances between the ring and pinion gears. The howling on coasting/decel goes away when you gas it, because it then forces the teeth into tight contact with each other.

 

Year, make, model?? Is your differential leaking(pinion seal leaks are common)? Have you checked the fluid level?

 

sorry about that its a 97 z28 30th yr fully stock. fluid level is perfect and there is no leaks around the pumpkin or any where elsea around the rear end..

 

Sounds like you've got a pinion bearing that's going out. That's the #1 symptom.

 

Well I had the same problem, and replaced the fluid with Amsoil. Whining went away

I figured it was wear, but it's possible that the fluid is just thinned out from time and abuse

Worth changing the fluid vs. installing new parts