I've got a pretty distinctive whine when driving my 87. It had the transmission fully rebuilt in November last year and I noticed it after getting it back from having it rebuilt. We took it out and he said he couldn't hear anything, drive it and let him know..

So many months later it had a slight leak, I took it back and he sorted that and I mentioned the noise again. He said it's the one way clutch. When you spin the driveshaft by hand it's quite noise at the tailshaft.

It's still bugging me now as something isn't right. Ive had three 3rd gens before this one and none have made this noise.

How can I check if its the rear diff though? Its a 9 bolt borg warner. I did change the fluid but it made no difference. I'm finding it hard to pinpoint the noise when driving as it could be coming from anywhere.

 

Does the noise change on accel/decel? Easiest way to determine if it's in the diff or trans would be to unbolt the driveshaft and spin each component independently of the other. That said, if the noise started after the build, it sorta narrows it down.

 

I've done that. It's quite noisy spinning the driveshaft at the transmission but that's what they sound like with the one way clutch. Spinning the back wheels with the driveshaft disconnected is quiet. But then the axle isn't really under any load is it? The noise starts as soon as you set off and get over like 5mph you can hear it. Its like a whistling/whine. Increases in pitch with the speed of the car.

 

Oscilloscope app on your phone will narrow it down to driveline speed or axle speed.

A mech. stethoscope while the car is rumming on jacks can help, but as said, if not under load, noises may not ahow up.

if axle speed and consistent with road speed, look at axle bearings.

Mostly vibration and driveline speed, check your play.

if it is a whine of a recognizable pitch, and changes on accel / decel, that's commonly rear gears.

 

For my 9 bolt, I had a whine that I thought was the transmission.... That I had just rebuilt... But when I ran the car on jackstands, it was the rear end.... And my 9 bolt needed a proper rebuild . It really was the pinion bearings... The inner one made the biggest difference.

Sound locations are very deceptive.....when driving....