Did you take the driveshaft out to see if the U-joint is seized? This is likely your problem as a seizing u-joint will not always present slop or play when you check it while still installed!
Here is a strange one. Truck is a '93 SR5, V6, 5speed, 4x4, 307k miles.
> Last week when I was backing out of a parking spot. I noticed a squeeking
> sound. Not a long squeek, but like a shopping cart wheel. Squeek, Squeek,
> Squeek. The noise is only when I put pressure on the drivetrain and I am
> under 5MPH. No noise when I go faster or I am coasting.
>
> I jacked the back of the truck up and took a look. The noise is comming
> from the rear diff near the U-joint. I lubed all the joints and the noise
> did not change. All the u-joints look in good shape. No slop and after a
> long drive, all where only warm to the touch.
>
> The rear diff, however, was hot. I don't think I could burn myself on it,
> but I didn't want to hold my hand on it for more then a few seconds.
> A year ago, I had the rear diff removed and inspected (with all the miles
> on it, I figured it was a good idea) and they guy said it looked hardly > used.
>
> No oil has been leaking out of the rear diff so I don't think it's been
> running dry. I plan to check soon tho.
>
> What is this squeeking noise? What do the bearings in the diff sound like
> when they are going out?
> I am stumped as to the cause of this.
>
> Thanks for any help.