Rear End Rumble when slowing down

Noticed that when I first start driving my truck, first couple stops I feel rear end vibration/rumbling. Noticed the vibration goes away after a little bit of driving.

Just changed differential fluid, using Valvoline Synpower

$30 75W-90 Synthetic Gear Lube - 1 Quart (Pack of 2)

75W-90, checked fuel level after changing and seemed good. What could be causing the issue?

2013 Tacoma Base

 

How did the fluid look? Was the magnet covered in goop and shavings?

Also are you certain it's not from the front? Could be your driver side clamshell bearing talking to you.

 

Not familiar with what the "clamshell" is....it's only RWD if that matters...

Fluid when I replaced it was black and smelled foul...changed at 33,000 miles, magnet had a small share of metal on it as well as goop.

Should I be concerned? I didn't use lsd adative if it matters

 

No additive needed with the electric "LSD"
If you're 2Wd, then no front diff (clamshell)
Diff fluid will be dark and a little goop on the magnet is normal.

 

Could be brakes. I'm out of ideas though.

 

And rear diff fluid is always stinky. You never forget that smell.

 

Anyone have any other ideas?

 

Bump

 

Okay, It's morning and my brain is working. Grease the zerks on your driveshaft. There's a good chance this will eliminate the noise. If that doesn't do it, move to the carrier bearing. Remove the CB bracket and rotate it 180 and bolt it back on. My money is on a sticky U joint though.

 

Not sure if this is like your problem and probably not what you want to hear, but from looking at your avatar it looks like you have a regular cab. My grandfather got a new base, 4cyl, regular cab and also had the same rumble/vibration like you're talking about. He took it to the dealer multiple times with no luck.

 

So should I stop worrying? Is this worth taking to the dealer?

 

Check the drive shaft u joint. Could be the culprit.

 

Follow up from my previous post...... If the grease bearing dries out in the u joint, the needle bearings inside the u joint will turn to dust and then there will be some play in the u joint, causing the vibration.

 

Won't it cause that "SqeakSqueakSqueakSqeakSqueakSqueak" sound if the joint were going out?

 

Is your truck a "5-lug" ?

 

Yes my truck is a 5 lug...is this a common issue?

 

I have a 5-lug company truck that I drive home everyday and sometimes when braking it looks as if the tranny is holding it in too high of a gear for the RPM's. The truck growls and vibrates until it down shifts. Look at your tach when it's happening. I don't care to get it looked at because I didn't pay for the truck.