I just replaced my rear pinion seal in my 99 150 9.75. It seemed to take some of the "whine" away from te rear end. Any ideas?? I thought the whine came from the backlash on the ring gear??

 

When you removed the pinion nut and seal you changed the pinion bearings preload. That changed the pitch of the whine.

I had a loose pinion nut and retightned. I was warned I may have problems later, but my loud whine went away. I picked up another 8.8 axle just in case. This was for '89, my 99' has the 10.25.

 

Ditto... the whine was being caused by the pinion bearings. Re-torquing the pinion flange nut may have changed the sound, but it's likely that the pinion bearings are already shot. You're going to want to have those replaced along with the crush washer sometime soon before the bearings grenade themselves. It's only a matter of time right now...

-Joe

 

After reading a bit this does not seem to be me just going to the dealership and getting a new bearing and poping it in correct? How much is invovled what kind of price should I look forward to paying?

 

Is this to include front and rear bearing??
I did not mention that the truck has whined for probably 50 or 60k.
Is there any way to honestly tell if the pinion bearings are bad before jumping into this??

 

To echo the statements from above, it is the pinion bearings that are making the whine more than likely. Mine usually started the whine when I would get up around 50-60MPH. It takes some work to get them replaced. Best left to someone who knows what they are doing, IMO. Once the bearings were out the mechanic showed me the "pitting" in the bearings. Mine only had the whine for about 3k miles, so yours are going to be a lot worse I would imagine.