I hate starting a thread for something that could probably be answered by searching, but I can't find much that pertains to doing the U-Joints on strictly a 2WD truck like mine, so here we are....


As has been well documented, there's two different size U-Joints that come up when you go looking for new ones, but trying to determine which ones are for what application is damn near impossible:
3.62" 5-178x (greaseable)/5-1350x (non-greaseable)/331 joint
4.18" 5-160x (greaseable)/5-1410x (non-greaseable)/330 joint


My 2WD truck only has a total of two U-Joints on the entire vehicle, one at the trans and one at the diff. It also does not have a slip joint, as it "slips" internally to the back of the trans. (Please correct me if you know of any of this to be wrong.) So does anyone know for sure which size the two U-Joints are on a 2000 7.3L 2WD Excursion?


The reason for why I'm asking is because my truck has developed a decently loud low growl from the rear, which I haven't been able to pinpoint yet. There is no vibration at all, just the growl, which absolutely does change with throttle application. Driving at a constant speed while feathering the throttle on and off is almost like flipping a switch between roar and no roar. This is a 250k mile truck that I've only owned for 21 months and ~15k miles.


So far I have completely swapped out the tires and wheels for another set just to rule those out, and that made no difference. The rear diff was a little wet, so I drained it, put a gasket on it, and replaced with Royal Purple. It was about 2/3rds of a quart low and the old fluid appeared pretty old, but changing it made no difference. Otherwise everything looked great inside the diff, with nothing built up on the magnets too bad. The next item I'm eyeing to replace is the U-Joints, despite them not appearing to have any play when pried on with a long pry-bar. But they've definitely been in there a long time. Does this sound like a logical place to be looking at, even though I have no vibration associated with this growl? I'm also wondering about the rear axle/wheel bearings, but I haven't found any sign of anything being loose or emitting excessive heat back there either.


I'm leaving on a ~3000-mile trip in two days, so I'm running out of time to deal with this. I'm actually almost to the point of "It's just a rumble but otherwise seems fine, so stop screwing with it until you don't have it to use at all.", which is what I'm worried about if I go and get some U-Joints this afternoon and try to get them installed this evening. I've also thought about just picking them up to have in the truck during the trip, just incase they do develop into a bigger problem that ends up really needing serviced while traveling.


Would appreciate your thoughts, especially form my fellow 2WD Excursion owners who've done U-Joints.

 

I can't help you on the part numbers, but as far as u-joints go... prying on them isn't the way to check them. Even if you pried at the right angle, you're trying to move an 8000# vehicle with a prybar. The correct way to do this is to jack the one or both rear wheels up (on level ground) and then check for movement with the weight of the vehicle off the driveline. If there is no play, changing them out probably won't do any good. There isn't always a vibration when they wear out. I've had them squeal, but never growl or vibrate.

So you are probably looking at a different problem. What's your mileage? Why do you think it's coming from the rear?

 

I cannot help you with which joint to get other than to call a Ford desk and ask for a part number.

I would much rather change them at home than in a parking lot or on the side of the road somewhere.

 

From the best I can gather, the 2WD should take two of the larger U-Joints, but I have yet to actually get that verified by anyone.


There's definitely no vibration associated with it, and I certainly wouldn't call it a squealing. It's a low growl/rumble/roar, that basically kicks on and off with application of the throttle.


It has 250k miles on it right now, and I don't really have any information about its maintenance history prior to me getting it with 235k miles on it.


I don't have any concrete evidence that it's for sure coming from the rear, other than assumptions based on experience. It most definitely sounds like it from the drivers seat, it's noticeably louder when you ride in the back, it's drivetrain related due to being throttle dependent, and it's a 2WD so you don't have the transfer case, carrier bearing, and way more U-Joints up in the front of the truck as you do in a 4WD.

 

I was thinking this before you said the mileage, which is why I asked. It almost sounds like gear noise. With that many miles, and now with that description of it being related to the throttle, it sounds even more like it. Gears and bearing wear down, tolerances slip, and noise starts to become noticeable.

I would probably change the u-joints anyway. It's not impossible they're the culprit and they're easy to change and eliminate as the source. I would also start saving for a rear axle rebuild. If you've ever thought about re-gearing it, this would be the time.

 

I'm in the same boat, but mine is a Lion's Roar now. I checked mine and believed that wasn't the problem, until a friend saw bare metal on the U joint. Guys told me that it was a my U joints, but ruled it, so just double check.

 

You can crawl under your excursion and measure them in less time it took write this post.

 

Does it sound like this?