Well, you've narrowed it down... Pull that drum and see what you find.

There aren't many options left...

 

Parking brake hardware failure?

 

I hate drum brakes... Always with the issues, also I hate drum brakes.

Anyway, after fighting with the drum to get it off from rust around the center... Initial inspection is actually quite good. Besides some dust covering everything as expected, the shoes were still in great shape.

Gallery of images, last two are afters.

Swapped in the kit, had a hell of a fight getting it all back in. Drum doesn't fit. Double check everything, make sure adjusters are closed all the way, etc. Same issue I had on the left side before. Tried sanding the shoes a bit before giving up and putting one of the old shoes back on. The pads on the new shoes are too thick. The old shoe still had 3/16" and the new ones were 1/4" so works for me.

Resolution? None. Everything is still as it was.... Grabbed a picture of my upper and lower balljoints on the passenger side while I was thinking about it to get opinions. I know it would have been better to take the wheel off, but it's 25 degrees, I'm frustrated, and didn't want to.

JointBalls

Idea now is rattling balljoints? I really don't want to think it's an axle bearing. Still waiting on that camera to arrive to record under the truck.

EDIT: I've pretty much resigned myself to replacing the axle bearings by now, doesn't seem too hard, just annoying. Since it seems to only complain while under load, I'll say it's still safe enough for light duty (i.e. haul trash) just not daily driver/long distance. If it starts rumbling while going straight, that'll stop as well. Gonna wait for a bit warmer weather before pulling the axles and changing those bearings.

Speaking of, bearings... bearings everywhere! Now there's a high pitch whine coming from the front of the engine between 900-1500RPM, around 2k it's gone. Seems to dissipate after the truck warms up enough to transfer heat into the pulleys. I'm hoping for idler pully or even tensioner pulley, as long as it isn't my alternator or water pump. I'll get a recording of this either tomorrow or this weekend, see what you guys think.

 

shocks and shock mounts OK? no evidence that they have bleed out?

 

Suspension parts seem fine..

Opinion Request: I'm planning on doing the rear axle bearings as the next step... Doesn't seem to hard, just annoying. My question to you is:

1: Bearings + seals
or
2: SKF repair bearing?

I don't know the condition of my axle and I prefer having the parts before digging into it to reduce any chance of contamination by letting it sit (I don't have a garage or anywhere I can leave it until parts show up). Should it be alright with just bearings and seals, or should I just opt for the repair bearing?

 

Well, my cheap camera came in finally and I managed videos this morning. Land it on my luck to get a chinese knockoff of a chinese knockoff, truly astounding. Snagged an SQ11 camera, by all the videos that people post they seem decent for being stupid cheap (paid a little over $9). They record 720p and "1080p" likely upscaled 720, but still decent. The one I received? Only does 480p and no wide lense like the actual SQ11. So the SQ11 is a knockoff of the Polaroid Cube, mine's a knockoff of the SQ11. Seller gave me a 50% refund when I mentioned it, but it was good enough to get video, audio? Not... quite so much. In quiet areas, the mic seems to be rather fine, but the exhaust of my truck makes the audio quite horrible and raspy, but I did get a bit of the chatter. Not much though, it seems harder to get it to make a sound when the rear diff oil is cold? (it's currently 18F outside).

Anyway here's the videos, I took one on each side with the camera zip-tied to the leaf springs.
Passenger side, best examples are around the 1:20-1:30 and the very last ~3 seconds.

Driver's side Best examples are around :35-:45 and 1:00-1:10 It's a little better since it's further from the exhaust.

Keep in mind, it only does this when turning left, and under load (it doesn't make a discernible noise coasting in a left turn 15-20 unless you hit the gas). Braking doesn't seem to have an effect on the noise if you take a banking curve a bit fast and really load the bearing.
I went ahead and ordered a pair of SKF R1559 repair bearings from RockAuto, turned out to be my cheapest quality option (without going cheap/no name bearings).

So now my question to all of you: Any recommendations, hints, or other info you can give about changing the rear axle bearings? The process seems straight forward, but I would like some information.

Diff: 8.25" 3.55 Open
1: How much and what weight gear oil?
2: Torque for diff bolts?
3: Torque for center pin bolt?
4: Tools required to rent?

 

REMOVAL - Axle Shaft
(1) Place the transmission in NEUTRAL and raise and support vehicle.
(2) Remove wheel and tire assembly.
(3) Remove brake drum (Refer to 5 - BRAKES/HYDRAULIC/MECHANICAL/DRUM - REMOVAL) ..
(4) Clean all foreign material from housing cover area.
(5) Remove the housing cover and drain lubricant.
(6) Rotate differential case to access the pinion shaft lock screw. Remove lock screw and pinion shaft from differential case (Fig. 16).
(7) Push axle shaft inward then remove axle shaft C-lock (Fig. 17).
(8) Remove axle shaft being carefull not to damage shaft bearing and seal.
(9) Inspect axle shaft seal for leakage or damage.
(10) Inspect axle shaft bearing contact surface for signs of brinelling, galling and pitting.

REMOVAL - Axle Bearing
(3) Remove axle shaft seal from the end of the axle tube with a small pry bar (Fig. 19).
(4) Remove axle shaft bearing with Bearing Removal Tool Set 6310 and Adapter Foot 6310-9 (Fig. 20).


INSTALLATION - Axle Bearing
(1) Wipe the axle tube bore clean. Remove any old sealer or burrs from the tube.
(2) Install the axle shaft bearing with Installer C-4198 and Handle C-4171. Ensure bearing is installed straight and the tool is in contacts with the axle tube when seating the bearing. NOTE: Install bearing with part number against the installer.
(3) Install a new axle seal with Installer C-4076-B and Handle C-4735-1. When the tool contacts the axle tube, the seal is installed to the correct depth.
(4) Coat the lip of the seal with axle lubricant for protection prior to installing the axle shaft.


INSTALLATION - Axle Shaft
(1) Lubricate bearing bore and seal lip with gear lubricant. Insert axle shaft through seal, bearing and engage it into side gear splines. NOTE: Use care to prevent shaft splines from dam- aging axle shaft seal lip.
(2) Insert C-lock in end of axle shaft. Push axle shaft outward to seat C-lock in side gear.
(3) Insert pinion shaft into differential case and through thrust washers and differential pinions.
(4) Align hole in shaft with hole in the differential case and install lock screw with Loctite on the threads. Tighten lock screw to 11 N·m (8 ft. lbs.).
(5) Install cover and fill with gear lubricant.
(6) Install brake drum (Refer to 5 - BRAKES/HY- DRAULIC/MECHANICAL/DRUM - INSTALLATION) .
(7) Install wheel and tire assemblies.
(8) Remove support and lower vehicle.

 

While the RTV is setting up a bit before I refill, figured I'd drop an update. Removing the differential cover revealed, at least, my gears seem to be in really good shape, no obvious wear, just shiny at the contact points. I'm reminded of how horrible gear oil smells, and greeted with I would guess a fairly typical, good rear diff. No metal shavings or such in the oil.

Here's a gallery of some images of my gears, a small video of them turning, and the bearings I took out.

Apparently you have to destroy the seals to get them out... Anyway, whole process took roughly 2.5 hours. This includes rebuild time... While I was under the truck after removing the center pin, someone rotated one of the axles and dropped my spider gears out... Had to fight to remesh them properly, then temporarily slipped the center pin back in to prevent it from happening again while I was working on the bearings. Despite clubbing my hand with the hammer three times while driving in the bearings, it wasn't too horrible a job. Made sure to prelube the bearing, seals, etc. got both axles loaded, c-clips, center pin, put a little locktite on the pin bolt and moved onto cleaning up the diff cover.

Holy hell, shoulda took some pictures, but the previous person who put bearings in apparently cheated on their spouse with some orange RTV they loved it so much. All the bolt holes were filled (pulled blobs off the ends of every bolt) had a thick layer, AND 1/4"-3/8" bead of squish out INSIDE the differential, and about the same outside. Luckily, 99% came off with the cover, quick wire brush shined up the diff. The cover itself took some razering before I could brush it clean. Had to clean all the bolts as well, they were covered all the way around.

I'll update this post after refilling with the 75W-90 full synthetic I grabbed and testing.

EDIT: Quick run around the parking lot says.... Sound still exists. Sigh.

Rundown of already done: brakes, pads and shoes, front rotors, front wheel hubs/bearings, rear brake kit, rear axle bearings. Suspension seems fine, no obvious leak on shocks.

 

Where are you at? I would love to go for a ride, and hear what you are experiencing.

 

In the south east middle of nowhere. Checking your profile location, about an 8.5 hour drive 500ish miles. I'd love to get a second opinion/look at it. I'm surrounded by ford guys that are willing to pay $800 for a sparkplug change, so none of them are helpful.