Whine from diff?

[Walsted]

I have a whine that sounds like it is coming from the rear of the car. It occurs when power is applied to the drivetrain to maintain or accelerate forward speed. Thus, in gear, clutch depressed, no whine. In gear, off of the accelerator, no whine. At high speeds, there is no whine I can hear, but it may be that the whine is at a frequency above human hearing. Differential fluid was replaced last spring (about 35,000 miles ago). I don't know if the transmission fluid was replaced during the engine swap last summer (about 30,000 miles ago).

Do I need to worry? Suggestions/advice?

[OZMDD]

Sounds like it's time for a diff rebuild. Check your bearings and drive shaft u joints too.

[Walsted]

Will check the drive shaft, thanks. Rear wheel beariings were changed about 10K miles ago.

[Gator Bait]

Will check the drive shaft, thanks. Rear wheel beariings were changed about 10K miles ago.

Even more reason to suspect them. Though my bet is on pinon bearing.

[Sharpie]

Mine was the front bearing on the diff.

[motorollow]

Sounds like it's time for a diff rebuild. Check your bearings and drive shaft u joints too.

+1. I would definitely eliminate these especially the u-joint. Front bearings are pretty easy to do.

[Rogue]

I've had several like that too, that I thought was the pinion……..Found one with the torsen DOA, in pieces in the bottom of the chunk.
If its the pinion JohnWag can fix you up.
PM John

[Walsted]

I think my torsen is still working, although I have occasionally abused it.

I'm guessing that checking the pinion bearing is just jacking up the rear of the car, putting the transmission in neutral, and checking for play and/or non-smooth rotation while rotating the driveshaft. Is that correct?

On a related note, if I have to replace the differential, and get a 3.9 instead of the 4.3, what is involved in making the speedo read correctly with the 5-speed?