My Chevy Astro has loud roar from rear end at speeds between 45 and 65. The noise occurs even in when I take it out of gear (neutral at those speeds). I have replaced ujoint, tires and had wheels aligned recently. Someone mentioned a rear transmission bearing and I am wondering if anyone else has advice on what to check next. The van has 152,000 miles on it. Thanks.

My Chevy Astro has loud roar from rear end at speeds between 45 and 65. The noise occurs even in when I take it out of gear (neutral at those speeds). I have replaced ujoint, tires and had wheels aligned recently. Someone mentioned a rear transmission bearing and I am wondering if anyone else has advice on what to check next. The van has 152,000 miles on it. Thanks.

As I understand it, this is a common problem with the Astro. My 91' had the same problem 100k miles ago and now has it again. This problem is caused by a bad pinnion bearing in the differential. I think thats what its called. Anyway its the bearing that supports the driveshaft as it enters the differential. I had a mechanic friend replace it for 300.00.
My brother used to work for the Ohio school district in which they had many Astro's and this problem was prevelent.

Does the vibration noise pulsate? Does the volume get loud then go away then get loud etc?

It will get louder and such because of differences in load, due to accelleration, etc..

Must be a different problem than mine. On my 2004 Astro the noise volume cycles up and down when holding a constant speed between 60 to 70 mph. Thanks.