Quick Driveline Vibe Questions

I'm trying to troubleshoot a noise which I suspect to be a driveline vibe, but so far I think I've asked all the wrong questions. So I'm going to start with some basics:

1. Does a driveline vibe happen at a certain speed or a certain RPM?

2. Could you hear a driveline vibe, but not feel it in the t-case handle?

Thanks,
Dave D.

Copy of my reply to your other post (mine is a 97):

1. Same thing after my Rocky Road 2 inch lift. Noise at 35mph.
Do a transfer case drop. I used 1 5/8" SuperStrut for a spacer ($15). You will need to cut it. You can also use this to lower your rear bump stops. You can get this in the electrical department at Home Depot.

Search this forum for drops...there are various ways...especially the bolt setup. You can also buy kits for more money...(same idea though).

You can also do the SYE and driveshaft, but then it will not be a "budget boost". Cost $350-500.

2. You won't feel it at the transfer case lever because it is mounted to the body tunnel. The transfer case is isolated from vehicle by the mount at the crossmember (the one you are going to drop). The vibration happens at the slip yoke at the tail of the TC.

3. Do a test by adding a bunch of washers and driving it. Then go to my item no. 1 for the fix.

4. If you go any higher, or plan to, budget and plan to do the SYE and DS solution. I am going to do the same.

Thanks, I plan on doing an SYE over a tcase drop. I knew it was a possibility, so it's in my Jeep budget.