Hey guys,
Been awhile. Starting playing with the car a bit more - now I'm back to the truck.
Truck started making a whining noise around spring '07. I chalked it up to the tires not getting rotated often enough and getting irregular wear. It got progressively a bit worse, and figured I would have to replace the tires, but didn't want to replace 1/2 worn tires. So I lived with the whine.
The noise makes itself known around 20mph, gets really loud (whole cab resonates it seems) around 40mph, subsides past 55mph and almost disappears at 70mph.
Fastforward to sept '07 when I took a diff sample (didn't get it to blackstone until feb 08, lazy). See the results attached, elevated iron. Blockhead me didn't make the connection.
Today got new tires. Noise still there. ARG . Jacked up the back of the truck, started it and ran the speedo to 20mph - same noise.
From searching the forums it seems like the bearings. That's what I'm going by.
Here's the kicker - leave tomorrow for a trip pulling the camper, get back in a week. Truck has been on about 12 towing trips since the noise showed up. I'm thinking it will be okay for one more trip before I get it to the shop. BTW I changed the diff fluid about one month ago. Noise hasn't gotten worse for months.
Thoughts? Is this caused by bad preload on the bearings (assuming it's bearings)?

Thanks...