I've noticed a strange trait of my totally stock '02 TJ. It's a mild "oscillation" at highway speed. It's almost unnoticeable; the only way I detected it was while driving with electronic noise canceling earbuds to block out some of the soft top roar on a short road trip.
The occurrence is as follows; you can feel a very slight vibration that comes on slowly, reaches its peak, and subsides, all within 1 to 2 seconds. The "non-oscillating" time is also just a few seconds in duration, and then the oscillation comes back. The vibration is nothing like DW, and feels more like a very mild U-joint issue or maybe a slight out of balance tire, but the fact that it comes and goes in a very consistent interval tells me it's not u-joint or tire.
I just read a post about the harmonic balancer on the txfer case of '02 models and it got me thinking about this.
Anyone ever experience this issue? Is there any need for concern? Since I can't even detect it without the earbuds in, I'm not thinking it's too serious, but I've also been a believer that any vibration left unattended will get worse....