2004 F-150 Heritage (older 2003 body) 2wd, 3.55LS rear with 4.2L and auto.

Went to accelerate hard from a stop while doing a lane change and heard something like crap rolling around in the bed and hitting the tailgate. When slowing to a stop I heard it again, this time more like a popping or grinding, not a whine. I could reproduce it in reverse with some throttle, and sometimes in forward. Any ideas?

My forum search yielded the following to check, and the results are also below:
U-joints. No play in the rear one. No play in the front one, but there is movement where the driveshaft (yoke?) enters the rear of the transmission. About 1/16th to maybe 1/8th. Is this normal?

Rear end. Had a light coating of lube front the front pinion seal. Checked the level, and tried to top it off, but it didn't take more than an ounce or two. The concern here was the fill plug. It had the normal gray metal muck like the transmission magnet, but also had a few slivers in it. is this normal or a sign of damage? Never been a fan of this LS rear.

Rear tire: Found this by shaking the hell out of the truck and al thing under it while I was there. The cable winch will move the cable, but once it starts to slip and ratchet it will not hold the tire as tight as I think it should. You can still push it around and it does make some noise, so I guess that could be it.

E-brakes. Post said broken brake hardware in the drum can cause popping. I pulled the drums on both sides and all looked well.

Rear axel bearing. While the drum was off I pulled on the axle and movement in and out is about 1/16 of an inch. Same or less in the up and down direction. Both sides are the same. I guess this is normal as well?

I think that's it. I drove it around the block and reversed it alot with no noise, so it could be the spare tire I removed, or the extra bit of lube to the diff. I'm worried about the front drive shaft where it pilots into the transmission and moved up and down a bit. Any help or ideas of what/how to check something further and rule it out would be greatly appreciated.

Fedds

 

Sound a lot like when my pinion bearing went out on my truck.

Coming back from the drag-strip(after racing one day) My truck started making a popping grinding sound when I would slow down and start from a stop. I pulled over and it did it in reverse too.
I got half way home before it locked up and I had to be towed. ):
The pinion went bad a the pinion was actually slid back in the pumpkin and the gear was grinding on the diff.

I would pull the cover off your rear and take a look in there,,especially if you have metal shavings in there.

 

Drove it to work today, about 25 miles. No noise on the freeway. Exited and came to stop, still no noise. The went to pull away and it sounded like tommy gun, popping and grinding. This time it did it long enough that whenever I was in a lower gear like 1st or 2nd it would make the sound. I'm pretty sure it's not just ground speed dependent, but engine speed and might be coming from the transmission. What would cause that?

 

I think your losing your rear end. its really not normal to have metal slivers on the magnet. have you ever changed the fluid? the stock 75w140 that came in it new should have been replaced awhile back when a tech bulletin came out saying that the FEHP oil that ford put in it from the factory was causing wear problems, i sucked all the fluid out of mine and replaced it with 85w140 and it runs really smooth. hope this helps.

 

Just to fill everyone in.

Had the truck towed to a local transmission shop to check the diff and transmission. They confirmed the transmission is the issue. $370 to remove and inspect it. I said go ahead after a low estimate of 795 and a high of about 2k. One of the planetary gear sets is broken and took out some other stuff. He rattled off the list of parts and kits. End total is $2500 for 1 year warranty. I told him to put it back together, and I'll have it towed to my house. And now he is starting to try and wheel and deal.

Some other options I looked at, but haven't decided on.
1) Jasper rebuilt unit. The list of upgraded parts for the 4R70W tranny looks decent. Looks like even for my 4.2L they will put the extra clutch disk in like the 5.4L gets, the upgraded 1-2 accumulator, etc. $2k for a 3yr, 100k mile warranty. Now the fine print. You need to have a certified Jasper installer or documentation of the flow and flushing of the cooling system. Flush in a can doesn't cut it. Called the certified installed in my area and he wants $750 to install it. I didn't call him back for 4 hours and now he is calling to cut a deal.
2)Autozone has a reman witha 3yr/36000 warranty for $1400. Don't know the details on the warranty though.
3)Junk yard tranny with ~50k is $650 with a 30day warranty. I've been told you might have to install up to 5 of these to get one that works. I can replace the tranny is a few hours (have a nice garage setup). I'm leaning this route and letting it become the dealer's problem on a trade in. I tow a boat most weekends and use my truck to haul stuff...I cna't be worried all the time about if the rebuilt will hold, or if the diff is about to go out.

Just sucks though...all my ford rangers had over 200k on them and still ran stong (totalled one at 130k, had one that the Odometer stopped working at 279k, another was sold with no issues at 230k). Pay 3x for a f150 and it doesn last 130k miles.

I'll try to get back on here with what I decide.

 

Well,
I played hardball with the transmission shop. I got a 3 year/36000 mile warranty for the $2400. I also got the $500 national warranty (breaks down anywhere and they will fix it with no extra cost to me) for free. Got that by telling them that FORD has this warranty and if I have any issue while on the road I can just have it towed to FORD, not back to Ohio. So hopefully three more years with my current truck and by then all the first time quality defects and bugs of the new model will be worked out.

Not sure if it's still true, but early on with the 4R70W the forward plantary gear set for the 5.4L was stronger than the rest of the models, so I told them to make sure to order that part for the replacement. Not that my 200HP 4.2L wil tear up the stock set, but it your going to do it you might as well do it right the first time.

Funny, with all my boat towing I would have thought I would have burned up a clutch or band and not busted a gear. I put a thermocouple on the output line from the transmission and you can definately tell that with the A/C a 20-30F rise in temps, and also when the t/c unlocks. I try to keep it around 180F, but I will let it rise to 200ish on the long hills. This truck in stock form does not have the external transmission cooler like the larger motor ones do. I might add one.

Looking back, all my leverage came from being able to walk away and threaten to install a junk yard or remanufactured transmission after they thought they had me for $400 for the drop and inspection. Also looking back and with all my research, I could have rebuilt this thing on my own. It's not that complicated and there are enough resources on the web and with a book or video it would have been a weekend job.

I am still going to pull the cover off the diff and take a peak at it, and change the fluid. The debris on the magnetic drain plug still has me a bit worried.

I'll be back to post any issues with the job or if I find an issue with the diff. Otherwise, I hope that helps someone else.