I'll try the pavement test the next time I get to town. I don't remember a problem with that but haven't done more than an occasional uturn.

I am near Missoula, Montana. I have wondered about the transfer case too. How do I tell if it is the case? I can turn the front drive shaft with the rear wheels on the ground with a great amount of effort. The transfer case being locked does make sense. It seem to act a lot like a 4x4 with the trans...

I could be wrong but I ruled out a rear diff. problem because the noise changes so much when I remove the front drive shaft. This makes it nearly quiet on the road and the hoist. With the front shaft in on the hoist, it makes the vibration. I do think there might be a bit of noise coming from the re...

Thanks for the quick ideas. The tires are the same and I've tried a set off of an older 2wd that I have. The tires from the 4wd don't shake on the other van either so I assume they don't have balance issues. What throws me off a bit is that it is much better with the front shaft off, and on the hois...

I have a 97 awd Astro with a high frequency vibration. It sounds like it is in the front end and begins at about 60mph. It has done this since I got it and have put on 16 thousand miles with no change. It seems to be better sometimes on wet and snowy roads. I can run it up to 70mph, put it in neutra...