2001 1500 Laramie rumble starts in high 50 MPS's only 50% of the time. Quits at 39.
 

I have had this 2001 1500 Laramie 5.9l long bed club cab for less than a year now. Just yesterday it started with a concerning problem: A deep rumble starts in high 50 MPS's only 50% of the time. Quits around 39. The rumble immediately stops when you let off the gas and no rumble when revving the engine in neutral. Thought i smelled a slight burning too so quickly brought it home and parked it. I am a novice but I did my best at a visual inspection looking for oil/grease leaks, loose looking bolts, and tears. I took pictures of somethings that may or may not be an issue. Well what could it be? Also I had the differential fluid/oil changed a few months ago on recommendation.

I don't see anything really unusual there. The output seal on what I guess is the t-case looks kinda wonky though... May wanna replace that just on general principles.

If it only makes the noise under power..... Check all your fluid levels, trans, t-case, differentials... and make sure everything is up to snuff.

Also, unload the drivetrain (block a couple wheels, put the trans in neutral) and have a look at all the u-joints, and the center support bearing. Wouldn't be surprised if that bearing wasn't getting old. (time to change it?)

Since it's only under power you hear it, gotta be in the rear drivetrain somewhere.

Welcome to DF! :D

Does it quit if you tap the brake while its acting up?

Thanks for your suggestion. After some google I did searches last night, I was thinking the Support Ball/Bering too. It might be. The fluids probably all need changed (except the differential, I just got that changed) So I'll have them done and see if anything changes and if not I'll get them to replace that ball. But first will do a bit more test driving and try reseting the power/computer (for sensors by unpluging the negative battery cable) and unplugging my newly installed brake controller and see if it is still doing it. And will check to see if taping the brakes affects the noise.

Question: what to look for on the u jonts and berring when "unloaded"

Either too much slop, (any at all is 'too much') or, binding. Either way, they need to go.

Well I took it to a shop and.......................Its the "Rear End" he says its bad with metal in it and he doesn't know how much bearings cost but thinks the cheapest option would be to get one from the junk yard. What do you think?

Also do I need the 3.21:1, 3.55:1 or 3.92:1 Ratio?

The gear ratio should be listed on a metal tag, help to the diff cover by one of the cover bolts.


Or,
It should also be on your build sheet, if you have gotten one off of the 'net.

Well I got a build sheet from the VIN and it says "3.55 Rear Axle Ratio". I still haven't decided to go with the junkyard or go with a rebuild or maybe even get a new one online. Does the differential come off the axle or do I need the "complete axle assembly"?

On here do I have to get one of the ones that say 5.9 since my truck is a 5.9L or can I get any of them: http://www.automotix.net/usedautopar...c4ee&seq_num=3 and also, is this just an axle or does it come with the differential too? Cause I would be upset if I ordered it and the differential is not there LOL. There is one that says in the description Description: "4X2 LOCKING" and I don't know what locking means. Would that one work if I ordered it?

Different engine size is just telling you what the axle came out of. There is no difference in the axle by engine size, they are the same, from the 3.9, to the 5.9.

You need the complete axle assembly. (minus the springs, unless yours are shot?)

Locking implies it has a limited slip differential. It's a traction aid. In a standard differential, the tire with the least traction gets ALL the power. With a locking diff, if one wheel starts slipping, the diff will transfer power to the other wheel.