Is this just road noise or is something wrong? I get a really loud bass rumble around 55~75 mph, it seems to oscillate in volume and it's coming from the back half. The only mods I have back there that could possibly be affecting it is a 2" lift.

 

Any chance you can get a recording of the sound? It's hard to figure it out with out hearing it..

 

i've got the same problem and have been trying to find a cure for my jeep for like 2 weeks.
help us on this one guys!

 

I replaced my muffler and cat and that cured my problem.
just like you described 55 + it would have a annoying rumble.

 

I'll try and post a recording of it tomorrow, maybe later tonight.

 

more than likely its a driveline angle issue. mine makes noise on occasion, i turn up the radio.

 

My u-joint on the drive shaft has a slight wiggle in it (I want to replace that joint, but I have no idea how.). That might be generating the noise then. I tried recording it, but my recording device (digital camera) couldn't pick it up.

 

that would be it

 

Maybe the problem is I'm too subtle with things like that... anyone have a link to a howto?